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Parenting behaviors have long been recognized as crucial to children's healthy development. However, examinations of the etiology of these behaviors are less prevalent. The current study investigated the driving forces behind parental warmth and discipline, particularly whether they are related more to traits within the parent or reactions to characteristics of the child. To explore this question, three robust factors of child temperament—effortful control, negative affectivity, and surgency/extraversion—and five parent personality traits were examined in association with parent behaviors through differential parenting within 185 four-year-old twin pairs (370 children; 56% girls; 90% White; predominantly middle class). Genetic analyses showed that parents tend to treat both children similarly in terms of parental warmth, but they treat children less similarly in terms of discipline, regardless of child zygosity. Multilevel linear regressions showed that within twin pairs, the child with higher effortful control received less discipline from parents than their cotwin. Analyses also showed that parent agreeableness was significantly related to parent warmth above and beyond other personality traits and child temperament. This study clarified the direction of effects and genetic contributions to parenting behaviors, supporting previous literature that discipline acts in reaction to the child, whereas warmth is more driven by parent personality. This research suggests the importance of focusing on child temperament and parent personality as they relate to parenting behaviors, allowing clinicians and parents to more effectively correct maladaptive parenting behaviors and encourage healthy and adaptive parenting behaviors, thus promoting positive outcomes for children. Public Significance Statement: This study clarified associations of parenting behaviors, indicating that children with lower effortful control than their siblings elicit more discipline from parents, whereas parental warmth is associated with parent personality (especially higher scores on agreeableness). If clinicians assess for these temperament and personality traits, they may be better able to effectively address the parent–child relationship, thus leading to improved outcomes for families. [ABSTRACT FROM AUTHOR]

Aim: Genetic influences on cerebral activity have been described previously, but data are scarce in preterms. We aimed to investigate whether a genetic influence causes amplitude-integrated electroencephalography (aEEG) signals to differ between singletons and twin preterm newborns. Methods: This was a retrospective single-centre study conducted at Innsbruck Medical University Hospital, Austria. Preterm infants born before 32 weeks of gestation between 6 November 2010 and 6 December 2022 were eligible for the study. The aEEG was analysed for the total maturation score, its component scores and the number of sleep--wake cycles per hour. Results: We enrolled 240 preterm twin infants (57.5% male) with a mean gestational age of 30 (range: 24-32) weeks and a mean birth weight of 1324 (range: 600--2116) grams. We compared 240 singleton matched preterms. No differences were found between preterm singletons and twin preterm infants regarding the total maturation and component scores, or the number of sleep--wake cycles. aEEG showed no difference between monozygotic and dizygotic twins. Conclusion: Compared to singletons, twin infants born preterm showed no differences in aEEG signals in the first 4 weeks of life. Future studies should include more complex non-invasive functional neuroimaging methods to gain more insight into this important topic. [ABSTRACT FROM AUTHOR]

Objectives Subjective health (SH) is not just an indicator of physical health, but also reflects active cognitive processing of information about one's own health and has been associated with emotional health measures, such as neuroticism and depression. Behavior genetic approaches investigate the genetic architecture of SH, that is, genetic and environmental influences on individual differences in SH and associations with potential components such as physical, cognitive, and emotional health. Previous twin analyses have been limited by sex, sample size, age range, and focus on single covariates. Methods The current analysis used data from 24,173 adults ranging in age from 40 to 90 years from the international Interplay of Genes and Environment across Multiple Studies consortium to investigate the genetic architecture of 3 measures of SH: self-rated health, health compared to others, and impact of health on activities. Independent pathways model of SH included physical health, depressive symptoms, and episodic memory, with age, sex, and country included as covariates. Results Most or all of the genetic variance for SH measures were shared with physical health, depressive symptoms, and episodic memory. Genetic architecture of SH differed across measures, age groups (40–65, 66–90), and sexes. Age comparisons indicated stronger correlations with all 3 covariates in older adults, often resulting from greater shared genetic variance. Discussion The predictive value of SH has been amply demonstrated. The higher genetic contributions to associations between SH and its components in older adults support the increasing conceptualization with age of SH as an intuitive summation of one's vital reserve. [ABSTRACT FROM AUTHOR]

The association between circadian rhythms and diseases has been well established, while the association with mental health is less explored. Given the heritable nature of circadian rhythms, this study aimed to investigate the relationship between genes underlying circadian rhythms and mental health outcomes, as well as a possible gene-environment correlation for circadian rhythms. Polygenic scores (PGSs) represent the genetic predisposition to develop a certain trait or disease. In a sample from the Netherlands Twin Register (N = 14,021), PGSs were calculated for two circadian rhythm measures: morningness and relative amplitude (RA). The PGSs were used to predict mental health outcomes such as subjective happiness, quality of life, and depressive symptoms. In addition, we performed the same prediction analysis in a within-family design in a subset of dizygotic twins. The PGS for morningness significantly predicted morningness (R 2 = 1.55%) and depressive symptoms (R 2 = 0.22%). The PGS for RA significantly predicted general health (R 2 = 0.12%) and depressive symptoms (R 2 = 0.20%). Item analysis of the depressive symptoms showed that 4 out of 14 items were significantly associated with the PGSs. Overall, the results showed that people with a genetic predisposition of being a morning person or with a high RA are likely to have fewer depressive symptoms. The four associated depressive symptoms described symptoms related to decision-making, energy, and feeling worthless or inferior, rather than sleep. Based on our findings future research should include a substantial role for circadian rhythms in depression research and should further explore the gene-environment correlation in circadian rhythms. [ABSTRACT FROM AUTHOR]

Background: The way in which socioeconomic status (SES) moderates the etiology of reading attainment has been explored many times, with past work often finding that genetic influences are suppressed under conditions of socioeconomic deprivation and more fully realized under conditions of socioeconomic advantage: a gene–SES interaction. Additionally, past work has pointed toward the presence of gene–location interactions, with the relative influence of genes and environment varying across geographic regions of the same country/state. Method: This study investigates the extent to which SES and geographical location interact to moderate the genetic and environmental components of reading attainment. Utilizing data from 2,135 twin pairs in Florida (mean age 13.82 years, range 10.71–17.77), the study operationalized reading attainment as reading comprehension scores from a statewide test and SES as household income. We applied a spatial twin analysis procedure to investigate how twin genetic and environmental estimates vary by geographic location. We then expanded this analysis to explore how the moderating role of SES on said genetic and environmental influences also varied by geographic location. Results: A gene–SES interaction was found, with heritability of reading being suppressed in lower‐ (23%) versus higher‐SES homes (78%). The magnitude of the moderating parameters were not consistent by location, however, and ranged from −0.10 to 0.10 for the moderating effect on genetic influences, and from −0.30 to 0.05 for the moderating effect on environmental influences. For smaller areas and those with less socioeconomic variability, the magnitude of the genetic moderating parameter was high, giving rise to more fully realized genetic influences on reading there. Conclusions: SES significantly influences reading variability. However, a child's home location matters in both the overall etiology and how strongly SES moderates said etiologies. These results point toward the presence of multiple significant environmental factors that simultaneously, and inseparably, influence the underlying etiology of reading attainment. [ABSTRACT FROM AUTHOR]

Fetoscopic laser coagulation of placental anastomoses is usually performed for a treatment of twin-to-twin transfusion syndrome (TTTS). A common complication of fetoscopic laser coagulation for TTTS is preterm preliminary rupture of fetal membranes (PPROM) aggravating the neonatal outcome significantly. However, use of an flexible 1 mm fetoscope with an curved sheath could reduce iatrogenic damage of the amniotic membrane and improve neonatal outcomes after laser treatment. The aim of this study was to compare neonatal outcomes using this flexible fetoscope with curved sheath vs. use of a standard lens technique. Outcomes were retrospective analyzed after use of a standard lens fetoscope of 2 mm (sheath 6.63 mm2 or 11.27 mm2 for anterior placenta) and a flexible fetoscope of 1 mm or 1.2 mm (sheath 2.65 mm2 or 3.34 mm2) in two German centers of fetal surgery, performed during 2006–2019. Neonatal outcome of 247 TTTS patients were analyzed including the rates of double and single fetal survival. The survival of at least one fetus was 97.2 % in the group with the ultrathin technique (n=154) compared to 88.3 % (n=93) in the group with the standard lens fetoscope (p=0.008). Survival of both fetuses was not different between groups (81.0 vs. 75.3 %). The procedure to delivery interval was significantly increased using the ultrathin fetoscope (89.1±35.0 d vs. 71.4±35.4 d, p=0.001) resulting in an increased gestational age at delivery by 11 days on average (231.9±28.1 d vs. 221.1±32.7 d, p=0.012). Fetal survival can be significantly increased following TTTS using flexible fetoscope of 1 mm or 1.2 mm (sheath 2.65 mm2 or 3.34 mm2) [ABSTRACT FROM AUTHOR]

Objective: The main risk factor for preterm delivery (PTD; <37 gestational weeks) is having a history of PTD. The aim of this research was to compare the risk for recurrent PTD following twin versus singleton gestation PTD. Methods: A retrospective population‐based cohort study was performed, including all women who had two consecutive pregnancies, the first of which ended with PTD. The incidence of PTD recurrence was compared between women with PTD in twin versus singleton gestation. Multivariable logistic models were used to study the association between twinning status and PTD recurrence, and specifically by gestational age of the first PTD, inter‐pregnancy interval (IPI), and mode of conception. Results: The study population included 15 590 women, of whom 1680 (10.8%) had twins in their index pregnancy and 13 910 (89.2%) had singletons. The incidence of recurrent PTD was 10.5% (n = 177) following twin PTD versus 21.9% (n = 3044) following singleton PTD (adjusted odds ratio = 0.50, 95% confidence interval 0.32–0.76, while controlling for confounding variables). The results were consistent while stratifying by IPI, gestational age of the first PTD, or mode of conception. Conclusions: Women with PTD in twin gestations are at lower risk for recurrent PTD compared with women with singleton PTD. Women with preterm delivery (PTD) in twin versus singleton gestations are at lower risk for recurrent PTD, regardless of gestational age, inter‐pregnancy interval or conception mode. [ABSTRACT FROM AUTHOR]

Objective: Congenital defects/diseases Background: The rarity of ischiopagus tripus conjoined twins complicates the surgical separation, owing to the lack of cases and high complexity. We aim to report our experience in performing orthopedic correction for ischiopagus tripus twins. Case Report: A pair of 3-year-old conjoined boys presented with a fused body at the pelvis region and only 1 umbilicus. There were 2 legs separated by shared genitalia and an anus at the midline, and 1 fused leg, which could be felt and moved by both of the patients. The twins also shared internal organs of the bladder, intestine, and rectum, as visualized through angiography computerized tomography scan. After several team discussions with the institutional review board, the hospital ethics committee, and both parents, it was agreed to perform disarticulation of the fused third limb, followed by correction of the trunk alignment by pelvic closed wedge osteotomy and internal fixation. We successfully reconstructed the pelvis using locking plates and additional 3.5-mm cortical screws and 1.2-mm stainless steel wire. Conclusions: This report describes the presentation and surgical management of a case of ischiopagus tripus conjoined twins. It highlights the challenges involved in surgery and the importance of investigating these infants for other congenital abnormalities. Although surgical approaches for different sets of twins should be individually tailored, interventions aimed to provide optimal outcomes should consider ethical issues and parental/patient expectations. Even in situations in which the twins are inseparable, there is still room for surgical correction to be performed. [ABSTRACT FROM AUTHOR]

Background: The social, economic, political, and emotional (SEPE) environment plays a crucial role in shaping human development both pre- and post-birth, with direct and independent effects on growth, as research shows. Objectives: This study examines the growth of twins and singletons and their association with maternal education as one of the social-economic (SE) variables. Methods: This cross-sectional study utilized Nutritional Status Monitoring for Children under 5 Years Old in Bandung District in September 2019. A total of 158 healthy children aged < 5 years, involving 35 twins (70 children) and 88 singletons, were included. Data on weight and length at birth and weight and length/height taken at age 8.6 to 60 months were plotted according to WHOCGS 2006. Statistical analyses and visualizations, including SE variables analysis, were conducted using density plots, correlation plots, St. Nicolas House Analysis (SNHA), and ANOVA. Results: At birth, z-scores of the body length, weight, and body mass index (BMI) of twins were lower than those of singletons (P < 0.05). After birth, z-scores of twins' length/height, weight, and BMI adjusted to those of singletons, with maternal education being the strongest among SE variables of early childhood growth adjustment. Conclusions: Twins were shorter, lighter, and had a lower average BMI at birth than singletons. There was no apparent association between birth measurements and SE variables. However, after birth, maternal education starts to gain a central position in regulating child growth. [ABSTRACT FROM AUTHOR]

The plastic deformation of TWIP steel is greatly inhibited during the expansion process. The stress–strain curves obtained through expansion experiments and observations of fracture morphology confirmed the low plastic behavior of TWIP steel during expansion deformation. Through an analysis of the mechanical expansion model, it was found that the expansion process has a lower stress coefficient and a faster strain rate than stretching, which inhibits the plasticity of TWIP steel during expansion deformation. Using metallographic microscopy, transmission electron microscopy, and EBSD to observe the twin morphology during expansion deformation and tensile deformation, it was found that expansion deformation has a higher twin density, which is manifested in a denser twin arrangement and a large number of twin deliveries in the microscopic morphology. During the expansion deformation process, dislocation slips are hindered by twins, the free path of the slips is reduced, and dislocations accumulate significantly. The accumulation area is the initial point of crack expansion. The results show that the significant dislocation accumulation caused by the delivery of a large number of twins under expansion deformation is the main reason for the decrease in the plasticity of TWIP steel. [ABSTRACT FROM AUTHOR]

To characterize the neonatal hemodynamic profiles in recipients born after twin-to-twin transfusion syndrome (TTTS) treated with fetoscopic selective laser coagulation (FSLC). Retrospective analysis during the first month of life of recipient twins. Of the 480 newborns born during an 11-year period, 138 recipient twins with prenatal FSLC were classified into four groups: no hemodynamic impairment (NoHI, n = 102, 74%), isolated high blood pressure (HighBP, n = 18, 13%), right ventricular outflow tract obstruction (RVOTO, n = 10, 7%), and cardiac failure (CF, n = 8, 6%). The time (median (IQR)) between FSLC and birth was significantly shorter in the HighBP (36 days (23–54)) and CF (44 days (18–54)) groups than in the RVOTO (91 days (68–112)) and NoHi (82 days (62–104)) groups (p < 0.001). Conclusion: Four distinct and well-characterized groups of recipients were identified based on their hemodynamics. High blood pressure and heart failure occurred in approximately 20% of the infants and were associated with a time between laser coagulation and birth of less than 2 months. What is Known: • Twin-to-twin transfusion syndrome (TTTS) is characterized by a hemodynamic imbalance that leads to high fetal and neonatal mortality if left untreated. One-third of recipient twins born without prenatal fetoscopic laser coagulation (FSLC) develop a life-threatening cardiac failure. What is New: • Four distinct groups of recipient twins with prenatal FSLC have been identified based on their hemodynamics. High blood pressure and cardiac failure occurred in 20% of the infants and were associated with an interval between FSLC and birth of less than 2 months. [ABSTRACT FROM AUTHOR]

Background: Findings from randomized trials (RCTs) on cervical pessary treatment to prevent spontaneous preterm birth are inconsistent. Objectives: Our hypothesis suggests that adhering to the European Medical Device Regulation (MDR) and following the instructions for use are essential prerequisites for successful therapy. Conversely, the non‐adherence to these guidelines will probably contribute to its failure. Search Strategy and Selection Criteria: Based on validated criteria from integrity assessments we performed a systematic review identifying 14 RCTs evaluating the effect of cervical pessaries. Data Collection and Analysis: We analyzed the implications of 14 criteria each accounting for 0–2 points of a score reflecting the clinical evaluation plan (CEP) as proposed by the MDR to evaluate the risk–benefit ratio of medical devices. Main Results: Seven RCTs in each singleton and twin pregnancies (5193 "cases") were included, detecting a high heterogeneity within control groups (I2 = 85% and 87%, respectively, P < 0.01). The CEP score varied from 11 to 26 points for all studies. The most common reasons for low scores and potential data compromise were poor recruitment rates, no (completed) power analysis, and no pre‐registration, but mainly non‐adherence to technical, biological, and clinical equivalence to the instructions for use as required by the MDR. All trials with score values greater than 20 had applied audit procedures. Within this group we found significantly reduced rates of spontaneous preterm birth at less than 34 weeks within the pessary group in singleton (odds ratio 0.28; 95% confidence interval 0.12–0.65) and twin pregnancies (odds ratio 0.30; 95% confidence interval 0.13–0.67). Similarly, there was a significant reduction in the composite poor neonatal outcome in singleton (odds ratio 0.25; 95% confidence interval 0.10–0.61) and twin pregnancies (odds ratio 0.54; 95% confidence interval 0.35–0.82) after a pessary as compared with controls. Conclusion: Non‐audited RCTs and meta‐analyses mixing studies of different clinical quality as pre‐defined by a CEP and the MDR pose the risk for erroneous conclusions. Synopsis: Our findings underline the importance of clinical audit procedures for randomized trials and specifically for the effect of cervical pessaries. [ABSTRACT FROM AUTHOR]

Background: Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic multiple gestation pregnancies, in which the pump twin provides hemodynamic support to a nonviable co-twin (acardius). Fetal magnetic resonance imaging (MRI) is used to detect pump twin abnormalities, particularly brain ischemia, prior to fetal intervention to interrupt umbilical blood flow to the acardius. Objective: To summarize the imaging findings of TRAP sequence pregnancies in a large series. Materials and methods: A single-center retrospective review was performed of all TRAP sequence pregnancies referred for fetal MRI (2004–2021). Fetal MRI, ultrasound, and echocardiography data were collected. Results: Eighty-eight TRAP sequence pregnancies with MRI were included (mean gestational age, 19.8±2.8 weeks). Demise of the pump twin was noted in two pregnancies at the time of MRI. By MRI, 12% (10/86) of live pump twins had abnormalities, including 3% (3/86) with brain abnormalities and 9% (8/86) with extra-cranial abnormalities. By echocardiography, 7% (6/86) of pump twins had structural cardiac abnormalities. Three acardius morphological subtypes were identified by MRI: acephalus (55%, 48/88), anceps (39%, 34/88), and amorphous (7%, 6/88). The mean ultrasound acardius to pump twin ratio A/P ratio, calculated for each twin pair as the ratio of the acardius trunk (and head, if present) plus limb volume to the pump twin estimated fetal weight) differed among the three acardius subtypes (P=.03). The mean A/P ratio moderately correlated with pump twin cardiothoracic ratio and combined cardiac output (Pearson's r=0.45 and 0.48, respectively, both P<.001). Conclusion: Fetal MRI of TRAP sequence pregnancies found anomalies in a substantial number of pump twins. The three acardius subtypes differed in A/P ratio, which moderately correlated with the pump twin cardiothoracic ratio and combined cardiac output. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine associations between life events and self-assessed loneliness in adolescence. We used data from a Norwegian population-based twin sample including seven birth cohorts (N = 2,879, 56% females). The participants completed self-report questionnaires three times throughout adolescence, with 2 years in between (i.e., 12–18 years old at Wave 1). By using a random intercept cross-lagged panel model (RI-CLPM), we were able to separate stable influences in the measured constructs from the within-person changes at each measurement occasion. In addition, using data from twins allowed us to examine to what degree the associations between life events and loneliness were genetic and/or environmental in nature. The results showed moderate stability of both loneliness and aggregation scores of life events throughout adolescence. The life events were assigned to clusters based on their independence (i.e., events considered dependent or independent on a person's behavior) and desirability (i.e., positive or negative). The time-stable between-person variance in all three measures, loneliness and person-dependent positive and negative life events, could almost exclusively be accounted for by genetic factors. However, as expected, also shared environmental factors influenced person-independent life events. The associations between time-stable between-person variance in loneliness and life events were small, and nearly exclusively due to shared genetic influences. Furthermore, life events do not seem to predict changes in loneliness or vice versa. In conclusion, the self-reported levels of loneliness throughout adolescence seems to be independent of life events. Public Significance Statement: This study suggests that life events do not influence levels of loneliness in adolescence. The weak associations between life events and loneliness were mainly due to shared genetic influences. Additionally, the results showed that levels of loneliness are moderately stable throughout this period of life, mainly due to genetic influences. Importantly, the study highlights the need of using genetically informative designs, also when studying the effects of assumed "environmental" measures. [ABSTRACT FROM AUTHOR]

Prior theoretical and empirical research has highlighted links between positive parenting and the socioeconomic characteristics of the family's neighborhood, but has yet to illuminate the etiologic origins of this association. One possibility is that the various predictors of parenting outlined by Belsky (1984; e.g., characteristics of the child, characteristics of the parent, and contextual influences) may matter more in some neighborhood contexts than in others. To examine this possibility, we conducted etiologic moderation analyses in a sample of 1,030 families of twins (average age 8 years; 51% male, 49% female; racial composition: 82% White, 10% Black, 1% Asian, 1% Indigenous, and 6% multiracial) from the Twin Study of Behavioral and Emotional Development in Children in the Michigan State University Twin Registry. Neighborhood and parenting were assessed using multiple informants and assessment strategies (neighborhood and family informants, administrative data, and videotaped parent–child interactions). Results pointed to strong evidence of etiologic moderation, such that child effects on positive mothering were prominent in neighborhoods with little opportunity and near zero in neighborhoods with ample opportunity. Such findings not only reframe the magnitude of child effects on the parenting they receive as context-dependent, but also indicate that mothers in impoverished neighborhoods may be more responsive to their children's characteristics than mothers in neighborhoods with ample opportunity. Public Significance Statement: Our findings confirm the long-running notion that children are active participants in the parenting they receive. However, we find that child effects on positive parenting are also context-dependent, such that child effects on positive parenting are especially pronounced in underresourced neighborhood contexts. [ABSTRACT FROM AUTHOR]

BACKGROUND ART is associated with higher rates of twin pregnancies than singleton pregnancies. Whether twin pregnancies conceived following ART have additional maternal and neonatal complications compared with non-ART twin pregnancies is not known. OBJECTIVE AND RATIONALE The objective was to quantify the risk of adverse maternal and perinatal outcomes among twin pregnancies conceived following ART compared with non-ART and natural conception. Existing reviews vary in the reported outcomes, with many studies including triplet pregnancies in the study population. Therefore, we aimed to perform an up-to-date review with an in-depth analysis of maternal and perinatal outcomes limited to twin pregnancies. SEARCH METHODS We searched electronic databases MEDLINE and EMBASE from January 1990 to May 2023 without language restrictions. All cohort studies reporting maternal and perinatal outcomes following ART compared with non-ART twin pregnancies and natural conception were included. Case–control studies, case reports, case series, animal studies, and in vitro studies were excluded. The Newcastle–Ottawa Scale was used to assess the methodological quality of the studies. Using random-effects meta-analysis, the estimates were pooled and the findings were reported as odds ratios (OR) with 95% CI. OUTCOMES We included 111 studies (802 462 pregnancies). Twin pregnancies conceived following ART were at higher risk of preterm birth at <34 weeks (OR 1.33, 95% CI 1.14–1.56, 29 studies, I 2 = 73%), <37 weeks (OR 1.26, 95% CI 1.19–1.33, 70 studies, I 2 = 76%), hypertensive disorders in pregnancy (OR 1.29, 95% CI 1.14–1.46, 59 studies, I 2 = 87%), gestational diabetes mellitus (OR 1.61, 95% CI 1.48–1.75, 51 studies, I 2 = 65%), and caesarean delivery (OR 1.80, 95% CI 1.65–1.97, 70 studies, I 2 = 89%) compared with non-ART twins. The risks for the above maternal outcomes were also increased in the ART group compared with natural conception. Of the perinatal outcomes, ART twins were at significantly increased risk of congenital malformations (OR 1.17, 95% CI 1.05–1.30, 39 studies, I 2 = 59%), birthweight discordance (>25% (OR 1.31, 95% CI 1.05–1.63, 7 studies, I 2 = 0%)), respiratory distress syndrome (OR 1.32, 95% CI 1.09–1.60, 16 studies, I 2 = 61%), and neonatal intensive care unit admission (OR 1.24, 95% CI 1.14–1.35, 32 studies, I 2 = 87%) compared with non-ART twins. When comparing ART with natural conception, the risk of respiratory distress syndrome, intensive care admissions, and birthweight discordance >25% was higher among the ART group. Perinatal complications, such as stillbirth (OR 0.83, 95% CI 0.70–0.99, 33 studies, I 2 = 49%), small for gestational age <10th centile (OR 0.90, 95% CI 0.85–0.95, 26 studies, I 2 = 36%), and twin–twin transfusion syndrome (OR 0.45, 95% CI 0.25–0.82, 9 studies, I 2 = 25%), were reduced in twin pregnancies conceived with ART versus those without ART. The above perinatal complications were also fewer amongst the ART group than natural conception. WIDER IMPLICATIONS ART twin pregnancies are associated with higher maternal complications than non-ART pregnancies and natural conception, with varied perinatal outcomes. Women seeking ART should be counselled about the increased risks of ART twin pregnancies and should be closely monitored in pregnancy for complications. We recommend exercising caution when interpreting the study findings owing to the study's limitations. [ABSTRACT FROM AUTHOR]

We assessed prevalence and correlates of differential maternal‐infant bonding (i.e., experiencing a stronger bond with one baby vs. the other) in mothers of twins, focusing on aspects of maternal mental health, well‐being, and pregnancy/birth that have been previously linked with maternal‐infant bonding. Participants (N = 108 American women, 88.89% White, 82.41% non‐Hispanic, aged 18–45, who gave birth to twins in the past 6–24 weeks) were recruited from postpartum support websites. Participants completed a Qualtrics survey assessing pregnancy/birth history, symptoms of depression and anxiety, sleep, stress, romantic relationship satisfaction, and postpartum bonding. Twenty‐six participants (24.07%) reported a bonding discrepancy. These participants endorsed higher symptoms of depression and anxiety, lower relationship satisfaction, lower average postpartum bonding, higher general and parenting stress, and longer pregnancy (all ps >.05). Greater degree of bonding discrepancy correlated with more depression, higher parenting stress, longer pregnancy, and lower relationship satisfaction (all ps >.05). Mothers of twins may benefit from postpartum mental health support, stress management strategies, and interventions to improve bonding. Future work should assess the role of breastfeeding difficulties, delivery method, birth‐related trauma, infant regulatory capacity, and temperament. Longitudinal studies will help test cause and effect and potential long‐term repercussions of maternal‐infant bonding discrepancies. [ABSTRACT FROM AUTHOR]

To investigate the clinical outcomes and Doppler patterns changes in monochorionic diamniotic (MCDA) twins with selective fetal growth restriction (sFGR). We retrospectively analyzed 362 sFGR cases from January 2010 to May 2016 at a single tertiary referral center. The Doppler waveforms of umbilical artery end-diastolic flow were collected, and all neonates were subjected to an early neonatal brain scan. A total of 66/100 (66 %) type I cases were stable, whereas 25/100 (25 %) cases changed to type II and 9/100 (9 %) changed to sFGR complicated twin-twin transfusion syndrome (TTTS). A total of 48.9 % (22/45) sFGR cases were complicated with polyhydramnios and 30.4 % (7/23) sFGR cases were complicated with oligohydramnios, both of which were progressed to sFGR with TTTS. Mild cerebral injury was significantly associated with Doppler flow abnormalities, earlier gestational age at delivery and type of sFGR diagnosis. Severe cerebral injury was significantly associated with gestational age at delivery (31.6 vs. 34.1, p=0.002) and larger birthweight discordance (43.9 vs. 29.3 %, p=0.011). Doppler patterns in sFGR can gradually change, with important consequences with regard to management and outcomes. Along with abnormal Doppler findings, earlier occurrence of sFGR and delivery are associated with subsequent neonatal cerebral injury. [ABSTRACT FROM AUTHOR]

Objectives This study aimed to assess the applicability of the National Academy of Medicine (NAM) interim guidelines for twin pregnancies to the specific population of gestational diabetes mellitus by exploring the relationship between gestational weight gain and adverse pregnancy outcomes in Chinese twin-pregnant women with gestational diabetes mellitus. Study Design This was a retrospective cohort study of women diagnosed with diabetes in pregnancy between July 2017 and December 2020 at the Maternal and Child Health Hospital in Chongqing, China. The primary variable of interest was maternal total gestational weight gain. The primary outcomes were perinatal outcomes, which included: preeclampsia, small for gestational age, large for gestational age, low birth weight, neonatal pneumonia, neonatal respiratory distress syndrome, and neonatal intensive unit admission, etc. The association between inappropriate gestational weight gain and adverse pregnancy outcomes was estimated using multiple logistic regression analysis. Results A total of 455 twin-pregnant women who had gestational diabetes mellitus were analyzed. Women with low gestational weight gain had reduced risk of preeclampsia (adjusted odds ratio [aOR], 0.32; 95% CI or confidence interval, 0.17–0.63; p = 0.001) and their infants had higher risks of small for gestational age (aOR, 1.93; 95% CI, 1.04–3.58; p = 0.037), low birth weight (aOR, 2.27; 95% CI, 1.32–3.90; p = 0.003), neonatal intensive unit admission (aOR, 3.29; 95% CI, 1.10–5.78; p = 0.038), pneumonia (aOR, 2.41; 95% CI, 1.08–5.33; p = 0.031), and neonatal respiratory distress syndrome (aOR, 2.29; 95% CI, 1.10–4.78; p = 0.027); the infants of women with excessive gestational weight gain had a higher risk of large for gestational age (aOR, 3.76; 95% CI, 1.42–9.96; p = 0.008). Conclusion Gestational weight gain controlled within the range recommended by the NAM could reduce the risk of perinatal adverse outcomes. The 2009 NAM gestational weight gain recommendations can be used for Chinese twin-pregnant women with gestational diabetes mellitus. Key Points Inappropriate gestational weight gain can lead to adverse perinatal outcomes in twin pregnancies. Gestational weight gain controlled within recommended range could reduce the risk of poor perinatal outcomes. The National Academy of Medicine recommendations are suitable for Chinese twin-pregnant women with GDM. [ABSTRACT FROM AUTHOR]

Existing evidence indicates genetic and non-genetic influences on sexual orientation; however, the possibility of gene-environment interplay has not been previously formally tested despite theories indicating this. Using a Finnish twin cohort, this study investigated whether childhood gender nonconformity and early-life adversities independently moderated individual differences in sexual orientation and childhood gender nonconformity, the relationship between them, and the etiological bases of the proposed moderation effects. Sexual orientation, childhood gender nonconformity, and early-life adversities were assessed using standard questionnaires. Structural equation twin model fitting was carried out using OpenMx. Childhood gender nonconformity was significantly associated with reduced phenotypic variance in sexual orientation (β = − 0.14, 95% CI − 0.27, − 0.01). A breakdown of the underlying influences of this moderation effect showed that this was mostly due to moderation of individual-specific environmental influences which significantly decreased as childhood gender nonconformity increased (βE = − 0.38; 95% CI − 0.52, − 0.001) while additive genetic influences were not significantly moderated (βA = 0.05; 95% CI − 0.30, 0.27). We also observed that the relationship between sexual orientation and childhood gender nonconformity was stronger at higher levels of childhood gender nonconformity (β = 0.10, 95% CI 0.05, 0.14); however, significance of the underlying genetic and environmental influences on this relationship could not be established in this sample. The findings indicate that beyond a correlation of their genetic and individual-specific environmental influences, childhood gender nonconformity is further significantly associated with reduced individual-specific influences on sexual orientation. [ABSTRACT FROM AUTHOR]

Objective: Reward‐based eating drives are putative mechanisms of uncontrolled eating implicated in obesity and disordered eating (e.g., binge eating). Uncovering the genetic and environmental contributions to reward‐related eating, and their genetic correlation with BMI, could shed light on key mechanisms underlying eating and weight‐related disorders. Method: We conducted a classical twin study to examine how much variance in uncontrolled eating phenotypes and body mass index (BMI) was explained by genetic factors, and the extent that these phenotypes shared common genetic factors. 353 monozygotic twins and 128 dizygotic twins completed the Reward‐based Eating Drive 13 scale, which measures three distinct uncontrolled eating phenotypes (loss of control over eating, preoccupation with thoughts about food, and lack of satiety), and a demographic questionnaire which included height and weight for BMI calculation. We estimated additive genetic (A), common environmental (C), and unique environmental (E) factors for each phenotype, as well as their genetic correlations, with a multivariate ACE model. A common pathway model also estimated whether genetic variance in the uncontrolled eating phenotypes was better explained by a common latent uncontrolled eating factor. Results: There were moderate genetic correlations between uncontrolled eating phenotypes and BMI (.26–.41). Variance from the uncontrolled eating phenotypes was also best explained by a common latent uncontrolled eating factor that was explained by additive genetic factors (52%). Discussion: These results suggest that uncontrolled eating phenotypes are heritable traits that also share genetic variance with BMI. This has implications for understanding the cognitive mechanisms that underpin obesity and disordered eating. Public Significance: Our study clarifies the degree to which uncontrolled eating phenotypes and BMI are influenced by shared genetics and shows that vulnerability to uncontrolled eating traits is impacted by common genetic factors. [ABSTRACT FROM AUTHOR]

Epigenetic clocks based on DNA methylation have been known as biomarkers of aging, including principal component (PC) clocks representing the degree of aging and DunedinPACE representing the pace of aging. Prior studies have shown the associations between epigenetic aging and T2DM, but the results vary by epigenetic age metrics and people. This study explored the associations between epigenetic age metrics and T2DM or glycemic traits, based on 1070 twins (535 twin pairs) from the Chinese National Twin Registry. It also explored the temporal relationships of epigenetic age metrics and glycemic traits in 314 twins (157 twin pairs) who participated in baseline and follow‐up visits after a mean of 4.6 years. DNA methylation data were used to calculate epigenetic age metrics, including PCGrimAge acceleration (PCGrimAA), PCPhenoAge acceleration (PCPhenoAA), DunedinPACE, and the longitudinal change rate of PCGrimAge/PCPhenoAge. Mixed‐effects and cross‐lagged modelling assessed the cross‐sectional and temporal relationships between epigenetic age metrics and T2DM or glycemic traits, respectively. In the cross‐sectional analysis, positive associations were identified between DunedinPACE and glycemic traits, as well as between PCPhenoAA and fasting plasma glucose, which may be not confounded by shared genetic factors. Cross‐lagged models revealed that glycemic traits (fasting plasma glucose, HbA1c, and TyG index) preceded DunedinPACE increases, and TyG index preceded PCGrimAA increases. Glycemic traits are positively associated with epigenetic age metrics, especially DunedinPACE. Glycemic traits preceded the increases in DunedinPACE and PCGrimAA. Lowering the levels of glycemic traits may reduce DunedinPACE and PCGrimAA, thereby mitigating age‐related comorbidities. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusion To compare the risk of intrapartum cesarean delivery (CD) between patients with twin and singleton pregnancies undergoing a trial of labor and identify risk factors for intrapartum CD in twin pregnancies.The present study was a retrospective cohort study of patients with a twin or singleton pregnancy who underwent a trial of labor at ≥340/7 weeks in a single center (2015–2022). The primary outcome was the rate of intrapartum CD. In twin pregnancies, this outcome was limited to CD of both twins. The association of plurality with intrapartum CD was estimated using multivariable Poisson regression.A total of 20 754 patients met the study criteria, 669 of whom had a twin pregnancy. Patients with twins had a greater risk of intrapartum CD (of both twins) than those with singleton pregnancies (22.1% vs 15.9%, respectively; aRR 1.38 [95% CI: 1.15–1.66]), primarily due to a greater risk of failure to progress. In addition, 4.1% of the twin pregnancies had a CD for the second twin, resulting in an overall CD rate in twin pregnancies of 26.2%. Variables associated with intrapartum CD in twin pregnancies included nulliparity (aOR 3.50, 95% CI: 2.34–5.25), birthweight discordance >20% (aOR 2.47, 95% CI: 1.27–4.78), and labor induction (aOR 1.64, 95% CI: 1.07–2.53). The rate of intrapartum CD was highest when all three risk factors were present (67% [95% CI: 41%–87%]).Twin pregnancies are associated with a greater risk of intrapartum CD than singleton pregnancies. Information on the individualized risk of intrapartum CD may be valuable when counseling patients with twins regarding mode of delivery. [ABSTRACT FROM AUTHOR]

The phenomenon of familial clustering in depression is well established, yet the mechanisms by which depression is transmitted within families remain poorly understood. In the current study, we investigate the familial genetic and environmental transmission of depression by incorporating data from both adolescent twins and their parents. A total of 987 twin families were recruited from the Beijing Twin Study. Depression assessments were conducted for both adolescents and their parents. Twins' depression was assessed through reports from both the twins themselves and their parents, while parental depression was assessed by parental self‐report. We employed a nuclear twin family model to examine genetic and environmental influences on adolescent depression. Our results, based on both self‐ and parent‐report, demonstrate significant additive and dominant genetic influences on depression. We also found mild yet significant sibling environmental influences, while familial environmental influences were absent. Notably, parent‐reported depression showed higher heritability but lower unique environmental influences compared with self‐reported depression. These results highlight the important role of genetic transmission and sibling environmental transmission in explaining depression. Our study delineates the underlying mechanism of familial transmission in depression and can inform early treatments to halt transmission during adolescence. [ABSTRACT FROM AUTHOR]

Background: Some preliminary research suggests higher rates of gastrointestinal disease in individuals with eating disorders (EDs). However, research is limited, and it remains unknown what etiologic factors account for observed associations. This was the first study to examine how EDs and dimensional ED symptoms (e.g. body dissatisfaction, binge eating) are phenotypically and etiologically associated with gastrointestinal disease in a large, population-based twin sample. Methods: Adult female (N = 2980) and male (N = 2903) twins from the Michigan State University Twin Registry reported whether they had a lifetime ED (anorexia nervosa, bulimia nervosa, or binge-eating disorder) and completed a measure of dimensional ED symptoms. We coded the presence/absence of lifetime gastrointestinal disease (e.g. inflammatory bowel disease) based on responses to questions regarding chronic illnesses and medications. We first examined whether twins with gastrointestinal disease had higher rates of EDs and ED symptoms, then used correlated factors twin models to investigate genetic and environmental contributions to the overlap between disorders. Results: Twins with gastrointestinal disease had significantly greater dimensional ED symptoms (β = 0.21, p < 0.001) and odds of a lifetime ED (OR 2.90, p = 0.001), regardless of sex. Shared genetic factors fully accounted for the overlap between disorders, with no significant sex differences in etiologic associations. Conclusions: Comorbidity between EDs and gastrointestinal disease may be explained by overlap in genetic influences, potentially including inflammatory genes implicated in both types of disorders. Screening for gastrointestinal disease in people with EDs, and EDs in those with gastrointestinal disease, is warranted. [ABSTRACT FROM AUTHOR]

Although previous studies have identified negative relationships between cognitive ability and emotional problems (EP), mechanism explaining these relationships remained unclear. This study evaluated two explanatory models using bivariate moderation model-fitting analysis in a twin design. The resilience model suggests that high cognitive ability decreases the risk of EP in adverse settings, and the scarring model suggests that EP symptoms lead to persistent cognitive deficits following onset. The Standard Progressive Matrices Plus (SPM) and EP scale were administered to a sample of 3,202 twins (mean age = 14.62 ± 1.74 years) attending public schools in Nigeria. The results of bivariate moderation model-fitting analyses only supported the resilience model. Moderation effects were not significant in the scarring model when genetic and environmental influences were incorporated. The best-fitting bivariate moderation model assuming the resilience model yielded a genetic correlation of − 0.57 (95% CI = − 0.40, − 0.84) with no significant environmental correlations. Moreover, the SPM moderated the environmental, not genetic, influences on EP, such that environmental influences were strong when protective factors were absent (low SPM) and weak when these were present (high SPM). These results indicate the need to develop targeted prevention and intervention strategies for EP in adolescents displaying low cognitive ability in deprived settings. [ABSTRACT FROM AUTHOR]

TwinsMX registry is a national research initiative in Mexico that aims to understand the complex interplay between genetics and environment in shaping physical and mental health traits among the country's population. With a multidisciplinary approach, TwinsMX aims to advance our knowledge of the genetic and environmental mechanisms underlying ethnic variations in complex traits and diseases, including behavioral, psychometric, anthropometric, metabolic, cardiovascular and mental disorders. With information gathered from over 2800 twins, this article updates the prevalence of several complex traits; and describes the advances and novel ideas we have implemented such as magnetic resonance imaging. The future expansion of the TwinsMX registry will enhance our comprehension of the intricate interplay between genetics and environment in shaping health and disease in the Mexican population. Overall, this report describes the progress in the building of a solid database that will allow the study of complex traits in the Mexican population, valuable not only for our consortium, but also for the worldwide scientific community, by providing new insights of understudied genetically admixed populations. [ABSTRACT FROM AUTHOR]

Between 2006 and 2021, the Hungarian Twin Registry (HTR) operated a volunteer twin registry of all age groups (50% monozygotic [MZ], 50% dizygotic [DZ], 70% female, average age 34 ± 22 years), including 1044 twin pairs, 24 triplets and one quadruplet set. In 2021, the HTR transformed from a volunteer registry into a population-based one, and it was established in the Medical Imaging Centre of Semmelweis University in Budapest. Semmelweis University's innovation fund supported the development of information technology, a phone bank and voicemail infrastructure, administrative materials, and a new website was established where twins and their relatives (parent, foster parent or caregiver) can register. The HTR's biobank was also established: 157,751 individuals with a likely twin-sibling living in Hungary (77,042 twins, 1194 triplets, 20 quadruplets, and one quintuplet) were contacted between February and March of 2021 via sealed letters. Until November 20, 2022, 12,001 twin individuals and their parents or guardians (6724 adult twins, 3009 parents/guardians and 5277 minor twins) registered, mostly online. Based on simple self-reports, 37.6% of the registered adults were MZ twins and 56.8% were DZ; 1.12% were triplets and 4.5% were unidentified. Of the registered children, 22.3% were MZ, 72.7% were DZ, 1.93% were triplets, and 3.05% were unidentified. Of the registered twins, 59.9% were female (including both the adult and minor twins). The registration questionnaire consists of eight parts, including socio-demographic and anthropometric data, smoking habits and medical questions (diseases, operations, therapies). Hungary's twin registry has become the sole and largest population-based twin registry in Central Eastern Europe. This new resource will facilitate performing world-class modern genetic research. [ABSTRACT FROM AUTHOR]

A review of an unusual twin type—twins born to women with two uteri (uterus didelphys)—is presented. This review is followed by summaries of recent research and perspectives concerning prenatal aneuploidy screening for twin pregnancies, twin conceptions by same-sex male couples, legal personality of conjoined twins, and a twin study of cannabis use. Interesting information about twins that has appeared in the media is also presented, namely how being taken for twins saved a pair of sisters; twin children of a jailed Nobel Prize winner, British 'biracial' twins, triplets born at the start of Russia's attack on Ukraine, and twins born in different years. [ABSTRACT FROM AUTHOR]

There is some evidence that in twin reversed arterial perfusion sequence, intervention at early gestational age could prevent a spontaneous death of the pump twin, achieving a better global survival. To review the perinatal outcomes of early intervention in pregnancies complicated by twin reversed arterial perfusion (TRAP) sequence. A comprehensive search from inception to December 2022 was conducted on databases including MEDLINE, EMBASE, Cochrane Library and LILACS. All studies that reported intervention in twin or triplet pregnancy complicated with TRAP sequence at 12 + 0 to 16 + 6 weeks of gestation were eligible. A descriptive and bivariate analysis was performed. Out of the 222 full-text articles, 44 studies reporting 108 cases of early intervention in TRAP sequence were included. A successful procedure was achieved in 105 (95.5 %) interventions: 89 (94.7 %) among twin pregnancies and 16(100 %) among triplet pregnancies. An overall livebirth rate was achieved in 75 patients (70.8 %): intrafetal laser group 55 (73.3 %), radiofrequency 10 (76.9 %) and endoscopic laser 3 (75.0 %). The median gestational age at delivery was 38 + 0 (37 + 4 – 39 + 4) weeks. The median treatment–delivery interval was 23 + 2 (IQR, 21 + 0–25 + 6) weeks. The most frequent adverse outcomes reported were preterm labor in 7 (13.7 %) patients. There were no severe adverse maternal outcomes. Early intervention with intrafetal laser and radiofrequency in TRAP sequence achieves a livebirth rate of the pump twin of about 75 %. [ABSTRACT FROM AUTHOR]

Background: The mode of delivery for twins born before 32 weeks of gestation remains controversial. Our purpose is to conduct a meta-analysis of twin pregnancies less than 32 weeks or twin weight less than 1500 g, so as to find a suitable delivery mode. Methods: We searched PubMed database, Cochrane Library database, and EMBASE database through December 2022. This protocol was registered with PROSPERO (CRD42023386946) prior to initiation. Studies that compared vaginal delivery to cesarean section for newborns less than 32 weeks of gestation or birthweight under 1500 g were included. The primary result was neonatal mortality rate. Secondary result was neonatal morbidity. The quality of literatures included in the research was evaluated in accordance with Newcastle–Ottawa Scale (NOS) literature quality evaluation scale. We use odds ratio (OR) as the effect index for binary variables. Point estimates and 95% confidence intervals (95% CI) were calculated. P < 0. 05 indicated statistically significant difference. Results: Our search generated 5310 articles, and a total of 8 articles comprising a total of 14,703 newborns were included in the analysis. The odds ratios of neonatal mortality rate were for twins delivered by vaginal delivery compared to cesarean section were 0.84 (95% CI 0.57–1.24, P = 0.38). The 5-min Apgar score < 7 (95% CI 0.44–1.75, P = 0.72), necrotizing enterocolitis (95% CI 0.81–1.19, P = 0.82), intraventricular hemorrhage (95% CI 0.41–1.86, P = 0.71), periventricular leukomalacia (95% CI 0.16–4.52, P = 0.84), bronchopulmonary dysplasia (95% CI 0.88–1.36, P = 0.42), and respiratory distress syndrome (95% CI 0.23–2.01, P = 0.48) were not statistically significant between the two groups. Conclusion: We have observed that vaginal delivery does not confer an increased risk of neonatal morbidity and mortality in twins born before 32 weeks of gestation. However, the current results are affected by substantial heterogeneity and confounding factors. We still need high-quality randomized-controlled studies require to address this important question. [ABSTRACT FROM AUTHOR]

The paper investigates the influence of gas dynamic cold spraying followed by laser processing of stainless steel samples on their dynamic (spallation) strength under the impact load at a 105 s–1 strain rate. The impact velocity effect on the microstructure and dynamic strength is studied herein. It is shown that the dynamic strength of steel samples after laser processing remains unchanged compared to unprocessed samples. Amorphization and melting are observed in the spallation region of the processed samples. Intense mechanical twinning develops inside austenite grains after the load application, and a largest number of twins is observed in unprocessed samples. [ABSTRACT FROM AUTHOR]

Emerging literature links neighborhood disadvantage to altered neural function in regions supporting socioemotional and threat processing. Few studies, however, have examined the proximal mechanisms through which neighborhood disadvantage is associated with neural functioning. In a sample of 7- to 19-year-old twins recruited from disadvantaged neighborhoods (354 families, 708 twins; 54.5% boys; 78.5% White, 13.0% Black, 8.5% other racial/ethnic group membership), we found that exposure to community violence was related to increased amygdala reactivity during socioemotional processing and may be one mechanism linking neighborhood disadvantage to amygdala functioning. Importantly, parenting behavior appeared to modulate these effects, such that high parental nurturance buffered the effect of exposure to community violence on amygdala reactivity. These findings elucidate the potential impact of exposure to community violence on brain function and highlight the role parents can play in protecting youth from the neural effects of exposure to adversity. Public Significance Statement: Although prior studies have primarily focused on family-level adversities, developmental researchers are now paying increased attention to the effect of neighborhood-level adversity on youth brain development. We find that increased exposure to community violence is related to heightened amygdala reactivity to threat and may be a mechanism explaining the link between neighborhood disadvantage and brain function in youth. Further, the study highlights that nurturing parenting can protect children from the risks posed by living in a disadvantaged and dangerous neighborhood. [ABSTRACT FROM AUTHOR]

Purpose: Previous studies have suggested that genetic factors are important in the development of degenerative disk disease (DDD). However, the concordance rates for the phenotypes requiring surgery are unknown. The purpose of this study was to determine the concordance rates for DDD requiring surgery by studying monozygotic (MZ) and dizygotic (DZ) twin pairs. Methods: Patients, aged between 18 and 85 years, operated for DDD between 1996 and 2022 were identified in the national Swedish spine register (Swespine) and matched with the Swedish twin registry (STR) to identify MZ and DZ twins. Pairwise and probandwise concordance rates were calculated. Results: We identified 11,207 patients, 53% women, operated for DDD. By matching the Swespine patients with the STR, we identified 121 twin pairs (37 MZ and 84 DZ) where one or both twins were surgically treated for DDD. The total twin incidence for operated DDD was 1.1%. For DDD requiring surgery, we found no concordant MZ pair and no concordant DZ pair where both twins were operated for DDD. When we evaluated pairs where at least one twin was operated for DDD, we found two concordant MZ pairs (the co-twins were operated for spinal stenosis) and two concordant DZ pairs (one co-twin operated for spinal stenosis and one (co-twin operated for disk herniation). Conclusions: Our findings suggest that genetic factors are probably not a major etiologic component in most cases of DDD requiring surgery. The findings of this study can be used for counseling patients about the risk for requiring DDD surgery. [ABSTRACT FROM AUTHOR]

This case explores the legal and ethical considerations for pediatricians surrounding gestational carrier pregnancies in the United States. Because of high success rates for assisted reproduction, state laws supporting same-sex adoption and surrogacy, and established legal precedents, gestational carrier pregnancies are increasingly common. The case presented involves a gestational carrier in preterm labor at 30 weeks' gestation with malpositioned twins who declines a cesarean delivery. Three commentaries are presented. The first highlights the importance of understanding the ethical implications of gestational carrier pregnancies in prenatal counseling. The second commentary emphasizes the pregnant person's right to autonomy and bodily integrity, and discusses considerations in surrogacy pregnancies, including the authority to authorize a cesarean delivery, valid informed consent, and decision-making for neonates. The third commentary discusses autonomy, emphasizing the importance of contracts in surrogacy pregnancies, and suggests that, in the case of a conflict between the gestational carrier and the intended parent(s), the gestational carrier's preference should be decisive regarding medical care during pregnancy. These discussions highlight key concepts for ethically informed and family-centered care in gestational carrier pregnancies and deliveries. [ABSTRACT FROM AUTHOR]

Introduction Twin-twin transfusion syndrome (TTTS) is a typical complication of monochorionic twin pregnancies (MCTP). Placental vessels that communicate in the chorionic plate between donor and recipient, are responsible for the imbalance of blood flow. Circulatory imbalance causes hypovolemia in donor and hypervolemia in recipient fetus. In a typical case, recipient fetus develops polyhydramnios, weight gain, cardiomegaly and hydrops fetalis. In contrast, donor fetus develops oligohydramnios and fetal growth restriction. Aim The objective of this review is to evaluate in detail the main diagnostic aspects and add other important data for diagnosis of TTTS. Scientific bases The main diagnostic event for this condition is based on the ultrasonographic discovery of oligohydramnios-polyhydramnios sequence. Other useful elements for diagnosis, staging and prognosis are fetal urinary bladder visualization, urinary bladder volumen measurements, edema of subcutaneous and/or generalized tissue edema, Doppler flow velocity waves and cardiac evaluation. Conclusion Considerations regarding diagnosis of TTTS make it possible to emphasize that role of physicians treating patients with MCTP is to identify ultrasound sequence of oligohydramnios-polyhydramnios. Other ultrasonographic fetal data as fetal urinary bladder visualization, urinary bladder volumen measurements, edema of subcutaneous and/or generalized tissue edema, Doppler flow velocity waves and cardiac evaluation; may help diagnosis, staging and prognosis of TTTS. It is their responsibility to accurately assess severity, therapeutic possibilities and prognosis. Key Points The role of physicians treating patients with MCTP, regarding diagnosis of TTTS, must be to identify ultrasound sequence of oligohydramnios–polyhydramnios. Other ultrasonographic fetal data may help diagnosis, staging, and prognosis of TTTS as follows: fetal urinary bladder visualization, urinary bladder volume measurements, edema of subcutaneous and/or generalized tissue edema, Doppler flow velocity waves, and cardiac evaluation. It is physicians' responsibility to accurately assess severity, therapeutic possibilities, and prognosis of patients with MCTP and diagnosis of TTTS. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to assess the maternal and neonatal outcomes associated with various obstetric management strategies in dichorionic twin pregnancies following fetal previable preterm premature rupture of membranes (PV-PPROM), in instances where the pregnancy is continued. Methods: In this case series, seven pregnancies involving dichorionic twins admitted with PV-PPROM before 23+6 weeks of gestational age were included, totaling 14 fetuses. The assessed parameters included demographic details, PPROM onset time, delivery time, duration of the latent period, cervical length upon hospitalization post-PPROM, cervical dilatation, white blood cell (WBC) count (103 /µL), C-reactive protein (CRP) levels (mg/L), obstetric examination findings, chosen obstetric management, outpatient follow-up, mode of delivery, neonatal mortality, APGAR score, cord pH, birth weight, and neonatal intensive care requirements. Results: The study encompassed seven pregnant individuals and 14 fetuses. The average maternal age was 31.2 years (range 24–43 years), with 57% of pregnancies being dichorionic twins resulting from in vitro fertilization. The mean gestational week at the time of PPROM was 16.8 weeks (ranging from 13 to 19+3). Among the cases studied, expectant management was employed in three cases, selective fetal reduction in two cases, and delayed-interval delivery in two cases. Neonatal outcomes revealed a 35% rate of live births and a 21% neonatal survival rate without significant morbidity. Conclusion: Managing obstetric care poses challenges following single fetal PV-PPROM in dichorionic pregnancies. Obstetric management should be personalised by evaluating the intrauterine localization of the fetus with PPROM, considering cervical examination findings, and taking into account chorioamnionitis findings. It is essential to engage in discussions with parents about potential risks and complications. [ABSTRACT FROM AUTHOR]

The contributions of genetic variation and the environment to gene expression may change across the lifespan. However, few studies have investigated the heritability of blood gene expression in older adults. The current study therefore aimed to investigate this question in a community sample of older adults. A total of 246 adults (71 MZ and 52 DZ twins, 69.91% females; mean age—75.79 ± 5.44) were studied. Peripheral blood gene expression was assessed using Illumina microarrays. A heritability analysis was performed using structural equation modelling. There were 5269 probes (19.9%) from 4603 unique genes (23.9%) (total 26,537 probes from 19,256 genes) that were significantly heritable (mean h2 = 0.40). A pathway analysis of the top 10% of significant genes showed enrichment for the immune response and ageing-associated genes. In a comparison with two other gene expression twin heritability studies using adults from across the lifespan, there were 38 out of 9479 overlapping genes that were significantly heritable. In conclusion, our study found ~24% of the available genes for analysis were heritable in older adults, with only a small number common across studies that used samples from across adulthood, indicating the importance of examining gene expression in older age groups. [ABSTRACT FROM AUTHOR]

Simple Summary: The fetal growth pattern in twin pregnancies is usually affected by the sex of the co-twin pairs, among other factors, with females being lighter than males at birth. We aimed to determine the effect of the sex of co-twins on lambs' birth weight in ovine pregnancies developed under natural undernourishment, a condition of sheep farming frequently encountered worldwide. Additionally, we sought to investigate whether the nutritional and/or antioxidant supplementation provided to ewes during pregnancy could modulate the potential effects associated with the sex of co-twins. We found that maternal nutrient restriction abolishes the sex differences in body weight at birth between co-twins. However, improving maternal nutrition and supplementation with antioxidants during gestation not only improves maternal weight and body condition but also tends to restore birth weight and its differences between female and male offspring, an effect that is enhanced with the combined supplementation of concentrated food and antioxidants. These results suggest that undernutrition not only may alter the intrauterine growth through the maternal–fetal relationship, but also through the feto–fetal relationship, which can be normalized via strategically targeting interventions such as maternal nutrient supplementation or antioxidant supplementation during gestation. Thus, a better understanding of the driving factors of this effect is of major relevance to improving fetal growth and lamb survival in harsh environments. In twin pregnancies of discordant sex, the male fetus grows larger than the female co-twin. Our study aimed to determine the effect of the sex of co-twins on lambs' birth weight in ovine pregnancies developed under natural undernourishment. Additionally, we investigated whether the nutritional and/or antioxidant supplementation provided to ewes during pregnancy could modulate the potential effects associated with the sex of co-twins. Ninety-six birth records of twin pregnancies of sheep grazing the natural Patagonian prairies were analyzed. The animals were divided into four groups: control (no supplementation), N (concentrate supplementation, 100% NRC), A (antioxidant supplementation), and NA (concentrate + antioxidant supplementation). Supplementation occurred from day 35 of gestation onwards until lambing. There were no differences in female or male birth weight in the control undernourished group. However, in group N, females or males with sex-discordant co-twins had a higher birth weight than did those with co-twins of the same sex. Group A males with female co-twins had a higher birth weight compared to males whose co-twins were also males. In NA lambs, males had a higher birth weight compared to females, regardless of their co-twin's sex. Therefore, chronic undernutrition abolished the differences in birth weight due to fetal sex. Restoring maternal nutrition or antioxidant supplementation tends to normalize birth weight and restore the differences between females and males. This effect is enhanced with the combined supplementation of concentrated food and antioxidants. [ABSTRACT FROM AUTHOR]

Background: Stress is a universal phenomenon and one of the most common precipitants of insomnia. However, not everyone develops insomnia after experiencing a stressful life event. This study aims to test aspects of Spielman's '3P model of insomnia' (during adolescence) by exploring the extent to which: (a) insomnia symptoms are predicted by polygenic scores (PGS); (b) life events predict insomnia symptoms; (c) the interaction between PGS and life events contribute to the prediction of insomnia symptoms; (d) gene–environment interaction effects remain after controlling for sex. Methods: The sample comprised 4,629 twins aged 16 from the Twin Early Development Study who reported on their insomnia symptoms and life events. PGS for insomnia were calculated. In order to test the main hypothesis of this study (a significant interaction between PGS and negative life events), we fitted a series of mixed effect regressions. Results: The best fit was provided by the model including sex, PGS for insomnia, negative life events, and their interactions (AIC = 26,158.7). Our results show that the association between insomnia symptoms and negative life events is stronger for those with a higher genetic risk for insomnia. Conclusions: This work sheds light on the complex relationship between genetic and environmental factors implicated for insomnia. This study has tested for the first time the interaction between genetic predisposition (PGS) for insomnia and environmental stressors (negative life events) in adolescents. This work represents a direct test of components of Spielman's 3P model for insomnia which is supported by our results. [ABSTRACT FROM AUTHOR]

Animal models suggest that experiencing high-stress levels induces changes in amygdalar circuitry and gene expression. In humans, combat exposure has been shown to alter amygdalar responsivity and connectivity, but abnormalities have been indicated to normalize at least partially upon the termination of stress exposure. In contrast, other evidence suggests that combat exposure continues to exert influence on exposed individuals well beyond deployment and homecoming, as indicated by longitudinal psychosocial evidence from veterans, and observation of greater health decline in veterans late in life. Accordingly, the experience of combat stress early in life may affect amygdalar responsivity late in life, a possibility requiring careful consideration of the confounding effects of aging, genetic factors, and symptoms of post-traumatic stress disorder. Here, we investigated amygdalar responsivity in a unique sample of 16 male monozygotic (MZ) twin pairs in their sixties, where one but not the other sibling had been exposed to combat stress in early adulthood. Forty years after combat experience, a generally blunted amygdalar response was observed in combat-exposed veterans compared to their non-exposed twin siblings. Spatial associations between these phenotypical changes and patterns of gene expression in the brain were found for genes involved in the synaptic organization and chromatin structure. Protein-protein interactions among the set of identified genes pointed to histone modification mechanisms. We conclude that exposure to combat stress early in life continues to impact brain function beyond the termination of acute stress and appears to exert prolonged effects on amygdalar function later in life via neurogenetic mechanisms. [ABSTRACT FROM AUTHOR]

Background The study explores whether frailty at midlife predicts mortality and levels of biomarkers associated with Alzheimer's disease and related dementias (ADRD) and neurodegeneration by early old age. We also examine the heritability of frailty across this age period. Methods Participants were 1,286 community-dwelling men from the Vietnam Era Twin Study of Aging at average ages 56, 62 and 68, all without ADRD at baseline. The cumulative deficit frailty index (FI) comprised 37 items assessing multiple physiological systems. Plasma biomarkers at age 68 included beta-amyloid (Aβ40, Aβ42), total tau (t-tau) and neurofilament light chain (NfL). Results Being frail doubled the risk of all-cause mortality by age 68 (OR = 2.44). Age 56 FI significantly predicted age 68 NfL (P  = 0.014), Aβ40 (P  = 0.001) and Aβ42 (P  = 0.023), but not t-tau. Age 62 FI predicted all biomarkers at age 68: NfL (P  = 0.023), Aβ40 (P  = 0.002), Aβ42 (P  = 0.001) and t-tau (P  = 0.001). Age 68 FI scores were associated with age 68 levels of NfL (P  = 0.027), Aβ40 (P  < 0.001), Aβ42 (P  = 0.001) and t-tau (P  = 0.003). Genetic influences accounted for 45–48% of the variance in frailty and significantly contributed to its stability across 11 years. Conclusions Frailty during one's 50s doubled the risk of mortality by age 68. A mechanism linking frailty and ADRD may be through its associations with biomarkers related to neurodegeneration. Cumulative deficit frailty increases with age but remains moderately heritable across the age range studied. With environmental factors accounting for about half of its variance, early interventions aimed at reducing frailty may help to reduce risk for ADRD. [ABSTRACT FROM AUTHOR]

Objective: To compare morbidity, as measured by length of stay in the neonatal intensive care unit (NICU), in twin and singleton gestations classified as small‐for‐gestational age (SGA) according to estimated fetal weight < 10th percentile on twin or singleton growth charts. Methods: NICU length of stay was compared in 1150 twins and 29 035 singletons that underwent ultrasound assessment between 35 + 0 and 36 + 6 weeks' gestation. Estimated fetal weight was obtained from measurements of head circumference, abdominal circumference and femur length using the Hadlock formula. Gestational age was derived from the first‐trimester crown–rump length measurement, using the larger of the two twins. Singletons and twins were compared in terms of NICU admission rate and length of stay according to classification as SGA by the Fetal Medicine Foundation singleton and twin reference distributions. Results: The overall proportions of twins and singletons admitted to NICU were similar (7.3% vs 7.4%), but twins tended to have longer lengths of stay in NICU (≥ 7 days: 2.4% vs 0.8%; relative risk (RR), 3.0 (95% CI, 1.6–4.4)). Using the singleton chart, a higher proportion of twins were classified as SGA compared with singletons (37.6% vs 7.0%). However, the proportion of SGA neonates entering NICU was similar (10.2% for twins and 10.1% for singletons) and the proportion of SGA neonates spending ≥ 7 days in NICU was substantially higher for twins compared with singletons (3.7% vs 1.4%; RR, 2.6 (95% CI, 1.4–4.7)). Conclusions: When singleton charts are used to define SGA in twins and in singletons, there is a greater degree of growth‐related neonatal morbidity amongst SGA twins compared with SGA singletons. Consequently, singleton charts do not inappropriately overdiagnose fetal growth restriction in twins and they should be used for monitoring fetal growth in both twins and singletons. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

This study examines the hypothesis that temperamental (dis)similarity is associated with twin relationship quality. In a longitudinal study that followed 322 monozygotic twins (who share close to 100% of their genes) and 1199 dizygotic twins (who on average, share 50% of their segregating genes) throughout childhood, mothers (N = 1547) and fathers (N = 536) reported on their twins' relationships on at least one of four measurement points when the twins were between 3 and 8–9 years of age. Mothers also reported on the twins' temperament. Negative associations were found between reports by both parents on the twins' closeness and their temperament difference throughout childhood, while positive associations were found between twins' conflict and their temperament difference in late childhood. Latent growth modeling indicated that the association between temperament differences and the twins' mother-reported closeness was evident beyond the effect of zygosity. A different pattern was found for twin conflict: the more the twins differed in their temperament (specifically negative emotionality) with age, the more the conflict between them increased. Our findings support the hypothesis that personality similarities can contribute to positive relationships from early childhood, and vice versa, beyond the effect of genetic similarity. [ABSTRACT FROM AUTHOR]

Attention-deficit/hyperactivity disorder (ADHD) and major depressive disorder (MDD) are two highly prevalent disorders that frequently co-occur. Prior evidence from genetic and cohort studies supports an association between ADHD and MDD. However, the direction and mechanisms underlying their association remain unclear. As onset of ADHD occurs in early life, it has been hypothesized that ADHD may cause MDD. We examined the association of ADHD with MDD using 3 different genetically informed methods to disentangle causality from confounding: 1) a nationwide longitudinal register-based full sibling comparison (N = 1,018,489) adjusting for shared familial confounding; 2) a prospective co-twin control study comprising 16,477 twins (5084 monozygotic and 11,393 dizygotic); and 3) a two-sample Mendelian randomization analysis using the largest available ADHD (N = 225,534) and MDD (N = 500,199) genome-wide association study summary statistics, adjusting for correlated and uncorrelated horizontal pleiotropy. Sibling and twin comparisons indicated that individuals with ADHD have an increased risk for subsequent development of MDD (hazard ratio = 4.12 [95% CI 3.62–4.69]) after adjusting for shared genetic and familial factors and that ADHD scores endorsed by parents are positively associated with subsequent MDD scores at ages 15 and 18 years (b = 0.07 [95% CI 0.05–0.08] and b = 0.09 [95% CI 0.08–0.11], respectively). Mendelian randomization analyses showed that genetic liability for ADHD is causally related to MDD (odds ratio = 1.15 [95% CI 1.08–1.23]). Our study provides consistent results across 3 different genetically informative approaches, strengthening the hypothesis that ADHD is causally related to MDD. [ABSTRACT FROM AUTHOR]

Objective: To assess whether the risk for future diabetes is higher among women diagnosed with gestational diabetes (GD) during twin versus singleton gestations. Method: A retrospective cohort study was performed including all women who delivered at a tertiary medical center between the years 1991 and 2021 and had at least one GD diagnosis. The first GD diagnosis per women was defined as the index pregnancy. Women diagnosed with GD during multiple gestations were compared with women diagnosed with GD during singleton gestations. The outcomes included first hemoglobin A1C (Hba1C) level > 6.4 mg/dL post partum, and the highest level measured during the follow‐up period of up to 30 years. Multivariable logistic and Cox proportional analysis were used to compare the risk between the two groups while adjusting for confounding variables. Results: The current study included 13 770 mothers, with 458 patients (3.3%) diagnosed with GD during twin gestations and 13 312 (96.7%) during singleton gestations. The mean follow‐up was 12.25 ± 9.3 years. Mothers of both groups did not differ in age at index pregnancy; however, mothers of twins were more likely to conceive following fertility treatments. Incidence of diabetes and prediabetes (defined as Hba1C > 6.4 and >5.7, respectively) were lower among the twin‐gestation group, both during the 6‐month postpartum period (for diabetes: 15.5% vs 22.1%; odds ratio [OR], 0.65 [95% confidence interval (CI), 0.46–0.91]) and during the long‐term follow‐up (for diabetes: 31.8% vs 40.7%; OR, 0.68 [95% CI, 0.52–0.88]). These results remained significant in the multivariable analysis, while accounting for age, ethnicity, and fertility treatments. Conclusion: GD diagnosis during multiple versus singleton gestations is associated with a lower risk for future diabetes. Synopsis: Women diagnosed with gestational diabetes during twin gestation are at lower risk for future diabetes, suggesting that gestational diabetes criteria should account for multiple gestation. [ABSTRACT FROM AUTHOR]

Multiple pregnancies involve several complications, most often prematurity, but also higher anomaly rates. Reducing fetuses generally improves pregnancy outcomes. We conducted this study to evaluate the obstetrical and neonatal results after multifetal pregnancy reduction (MFPR) in the largest tertiary hospital in Finland. This retrospective cohort study included all MFPR managed in Helsinki University Hospital during a 13 year period (2007–2019). Data on pregnancies, parturients and newborns were collected from patient files. The number of fetuses, chorionicities and amnionicities were defined in first-trimester ultrasound screening. There were 54 MFPR cases included in the final analyses. Most often the reduction was from twins to singletons (n=34, 63 %). Majority of these (25/34, 73.5 %) were due to co-twin anomaly. Triplets (n=16, 29.6 %) were reduced to twins (n=7, 13 %) or singletons (n=9, 16.7 %), quadruplets (n=2, 3.7 %) and quintuplets (n=2, 3.7 %) to twins. Most (33/54, 61.1 %) MFPR procedures were done by 15+0 weeks of gestation. There were six miscarriages after MFPR and one early co-twin miscarriage. In the remaining 47 pregnancies that continued as twins (n=7, 14.9 %) or singletons (n=40, 85.1 %) the liveborn rate was 90 % for one fetus and 71.4 % for two fetuses. Most MFPR cases were pregnancies with an anomalous co-twin. The whole pregnancy loss risk was 11.1 % after MFPR. The majority (70.6 %) of twins were spontaneous, whereas all quadruplets, quintuplets, and 56.3 % of triplets were assisted reproductive technologies (ART) pregnancies. Careful counselling should be an essential part of obstetrical care in multiple pregnancies, which should be referred to fetomaternal units for MFPR option. [ABSTRACT FROM AUTHOR]

Introduction: We present a unique case of monozygotic female twins with virtually identical clinical and radiological presentations of supratentorial hydrocephalus and cystic formations from the suprasellar cistern. Discussion: Evaluating genetic predispositions and prenatal exposures is crucial for hydrocephalus in twins. Familial cases imply a genetic contribution to the development of these anomalies, including chromosomal abnormalities and specific variants linked to arachnoid cyst formation in various syndromes. Extensive genetic analyses found no pathogenic variants in the twins. Prenatal exposure to anti-epileptic medication was known during pregnancy and may be associated with fetal abnormalities, but not central nervous system (CNS) malformations, and was therefore not considered the cause of the condition in the twins. The twins presenting simultaneously with hydrocephalus caused by suprasellar cysts (SAC) underwent a two-step surgical management: initial ventriculoperitoneal shunt (VPS) placement followed by fenestration. Postoperative imaging showed cyst reduction, but a secondary VPS was necessary in both cases. Conclusion: Genetic analysis is less likely to identify a monogenic etiology in non-syndromic cases of SACs, which are assumed to be multifactorial. There is no established evidence linking a teratogenic effect of anti-epileptic drugs to CNS malformations. Moreover, the surgical treatment of this complex condition constitutes a point of discussion. [ABSTRACT FROM AUTHOR]

Background: To date, there are no clinical guidelines for dichorionic diamniotic (DCDA) twins complicated with previable premature rupture of membrane (PV-ROM) before 24 weeks of gestation. The typical management options including expectant management and/or pregnant termination, induce the risks of fetal mortality and morbidity. Objective: To explore the feasibility selective feticide in DCDA twins complicated with PV-ROM. Study design: A Retrospective cohort study, enrolling 28 DCDA twins suffering from PV-ROM in a tertiary medical center from Jan 01 2012 to Jan 01 2022. The obstetric outcome was compared between selective feticide group and expectant management group. Results: There were 12 cases managed expectantly and 16 underwent selective feticide. More cases suffered from oligohydramnios in expectant management group compared to selective feticide group (P = 0.008). Among 13 cases with ROM of upper sac, the mean gestational age at delivery was (33.9 ± 4.9) weeks in the selective feticide group, which was significantly higher than that in the expectant management (P = 0.038). Five fetuses (83.3%) with selective feticide delivered after 32 weeks, whereas only one (14.3%) case in expectant management group (P = 0.029). However, in the subgroup with ROM of lower sac, no significant difference of the mean gestation age at delivery between groups and none of cases delivered after 32 weeks. Conclusion: There was a trend towards an increase in latency interval in DCDA twins with PV-ROM following selective feticide, compared to that with expectant management. Furthermore, selective feticide in cases with PV-ROM of upper sac has a favorable outcome. [ABSTRACT FROM AUTHOR]

Background: Previous studies of singletons evaluating prenatal phthalate exposure and early neurodevelopment reported mixed results and the associations could be biased by parental, obstetrical, and genetic factors. Methods: A co-twin control design was employed to test whether prenatal phthalate exposure was associated with children's neurocognitive development. We collected information from 97 mother-twin pairs enrolled in the Wuhan Twin Birth Cohort between March 2016 and October 2018. Fourteen phthalate metabolites were measured in maternal urine collected at each trimester. Neurodevelopmental differences in twins at the age of two were examined as the outcome of interest. Multiple informant model was used to examine the covariate-adjusted associations of prenatal phthalate exposure with mental development index (MDI) and psychomotor development index (PDI) scores assessed at 2 years of age based on Bayley Scales of Infant Development (Second Edition). This model also helps to identify the exposure window of susceptibility. Results: Maternal urinary levels of mono-2-ethyl-5-oxohexyl phthalate (MEOHP) (β = 1.91, 95% CI: 0.43, 3.39), mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) (β = 1.56, 95% CI: 0.33, 2.79), and the sum of di-(2-ethylhexyl) phthalate metabolites (∑DEHP) (β = 1.85, 95% CI: 0.39, 3.31) during the first trimester showed the strongest and significant positive associations with intra-twin MDI difference. When stratified with twin chorionicity, the positive associations of monoethyl phthalate (MEP), monoisobutyl phthalate (MiBP), mono-n-butyl phthalate (MBP), monobenzyl phthalate (MBzP), individual DEHP metabolites, and ∑DEHP exposure during pregnancy with intra-twin neurodevelopmental differences were more significant in monochorionic diamniotic (MCDA) twins than those in dichorionic diamniotic (DCDA) twins. Conclusions: Neurodevelopmental differences in MCDA twins were strongly associated with prenatal phthalate exposure. Our findings warrant further confirmation in longitudinal studies with larger sample sizes. [ABSTRACT FROM AUTHOR]