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Background/objective: Previous studies have consistently demonstrated that maternal weight status both before and during pregnancy is associated with infant birthweight. However, a fundamental limitation across this literature remains that previous studies have not evaluated the concomitant impact of paternal weight at conception, owing to the paucity of studies in which fathers were assessed prior to pregnancy. Thus, we established a cohort of preconception couples to prospectively evaluate the associations of maternal and paternal weight prior to pregnancy with infant birthweight at delivery., Methods: In this prospective observational cohort study, 1292 newly-married women and their partners in Liuyang, China, were assessed at median of 23.3 weeks before a singleton pregnancy, thereby enabling concomitant assessment of preconception maternal and paternal body mass index (BMI) in relation to infant birthweight., Results: Mean birthweight was 3294 ± 450 g with 147 neonates (11.4%) born large-for-gestational-age (LGA) and 94 (7.3%) small-for-gestational-age (SGA). After adjustment for maternal and paternal factors prior to conception (age, education, smoking, BMI, household income), length of gestation, total gestational weight gain, gestational diabetes, preeclampsia, and infant sex, it was noted that infant birthweight increased by 42.2 g (95% CI 29.5-54.8; p < 0.0001) per unit increase in maternal pregravid BMI and 10.7 g (95% CI 0.5-20.9; p = 0.04) per unit increase in paternal pregravid BMI. Maternal pregravid BMI explained 6.2% of the variance in birthweight whereas paternal BMI explained only 0.7%. Independent predictors of LGA delivery were maternal pregravid BMI (aOR = 1.91, 95% CI 1.50-2.44), maternal age (aOR = 1.48, 95% CI 1.09-2.00), and gestational weight gain (aOR = 1.80, 95% CI 1.40-2.30). Paternal pregravid BMI was not independently associated with LGA or SGA., Conclusion: Paternal BMI prior to conception is associated with infant birthweight but only modestly so, in contrast to the dominant impact of maternal weight., (© 2021. The Author(s).)

Physical activity (PA) may modify the genetic effects that give rise to increased risk of obesity. To identify adiposity loci whose effects are modified by PA, we performed genome-wide interaction meta-analyses of BMI and BMI-adjusted waist circumference and waist-hip ratio from up to 200,452 adults of European (n = 180,423) or other ancestry (n = 20,029). We standardized PA by categorizing it into a dichotomous variable where, on average, 23% of participants were categorized as inactive and 77% as physically active. While we replicate the interaction with PA for the strongest known obesity-risk locus in the FTO gene, of which the effect is attenuated by ~30% in physically active individuals compared to inactive individuals, we do not identify additional loci that are sensitive to PA. In additional genome-wide meta-analyses adjusting for PA and interaction with PA, we identify 11 novel adiposity loci, suggesting that accounting for PA or other environmental factors that contribute to variation in adiposity may facilitate gene discovery.

Background: Excessive gestational weight gain is associated with postpartum weight retention and downstream child obesity. Dopamine plays a critical role in the regulation of energy intake and body weight. The purpose of this study was to examine the relationship between excessive gestational weight gain and dopamine pathway-related polymorphisms, namely the variable nucleotide tandem repeat in the 3'untranslated region (UTR) region of the SLC6A3 (DAT-1) dopamine transporter gene and the 30-base pair variable nucleotide tandem repeat polymorphism of the 5'UTR of the monoamine oxidase-A (MAO-A) gene. Methods: Ninety-three women of mean age 31.7 ± 4.2 years were recruited from the Ottawa and Kingston birth cohort and assessed at 12-20 weeks' gestation. Mean body mass index was 22.7 ± 2.5 kg/m2. Excessive gestational weight gain was defined according to the 2009 Institute of Medicine guidelines based on body mass index. Genotype analyses were performed using polymerase chain reaction and agarose gel electrophoresis. Results: There was no relationship between the prevalence or magnitude of excessive gestational weight gain among women with the 3' UTR single nucleotide polymorphism of the DAT-1 gene. However, 70% (19 of 27) of women carrying the MAO-A 4/4 (high activity) allele exceeded recommendations for gestational weight gain compared with 48% (32 of 60) of those with the pooled 3/3, 3/4, and 3/3.5 (low activity) alleles (P < 0.05). Similarly, those with the MAO-A 4/4 allele had significantly greater gestational weight gain than those with the 3/3, 3/4, or 3/3.5 pooled genotypes (19.3 ± 4.1 versus 17.0 ± 5.0 kg, P = 0.03). Conclusion: Carriers of the 4/4 variants of the MAO-A gene may be at increased risk for excessive gestational weight gain [ABSTRACT FROM AUTHOR]

Objectives: To compare outcomes of neonates born from women with Class III obesity with those whose mothers were of normal body weight. Methods: A retrospective cohort study of live-born singleton infants was undertaken. Maternal prepregnancy body mass index (BMI) defined matched normal and Class III obese cohorts. Multivariable regression models were used to determine adjusted relative odds ratios (aOR) and 95% confidence intervals (CI) for selected adverse neonatal outcomes. Results: Newborns exposed to maternal Class III obesity had greater risks of fetal overgrowth and low cord artery pH. Class III obesity was protective against small for gestational age and low birthweight. There was no difference in the risk of preterm delivery, meconium in the amniotic fluid or breastfeeding initiation. Conclusions: The new knowledge generated by this study provides further information on unique challenges faced by newborns of women with Class III obesity, suggesting more specialized care in the intrapartum and neonatal periods may be beneficial. [ABSTRACT FROM AUTHOR]

Obesity is a major health problem, and many family-based studies have suggested that it has a strong genetic basis. We performed a genome-wide quantitative trait linkage scan for loci influencing BMI in 573 pedigrees from the U.K. We identified genome-wide significant linkage (logarithm of odds = 3.74, between D10S208 and D10S196, genomewide P = 0.0186) on chromosome 10p. The size of our study population and the statistical significance of our findings provide substantial contributions to the body of evidence for a locus on chromosome 10p. We examined eight single nucleotide polymorphisms (SNPs) in GAD2, which maps to this linkage region, tagging the majority of variation in the gene, and observed marginally significant (0.01 < P < 0.05) associations between four common variants and BMI. However, these SNPs did not account for our evidence of linkage to BMI, and they did not replicate (in direction of effect) the previous associations. We therefore conclude that these SNPs are not the etiological variants underlying this locus. We cannot rule out the possibility that other untagged variations in GAD2 may, in part, be involved, but it is most likely that alternative gene(s) within the broad gene-rich region of linkage on 10p are responsible for variation in body mass and susceptibility to obesity. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine associations between maternal age and maternal request cesarean deliveries. Study design: Five-year population-based data from Taiwan (1997-2001) that covered 904,657 singleton deliveries without a clinical indication for cesarean delivery that were judged by the attending physician were subjected to multiple logistic regression, year-wise, to examine the association of maternal age with request cesarean delivery, adjusted for health care institutional characteristics. Results: Request cesarean delivery rates steadily increased over the study period within each age group, disproportionately so among the 34 + age group. Women aged <25 years were less likely than women aged 25 to 34 years (reference group) to request a cesarean delivery (odds ratio range, 0.67-0.88) and women aged 34+ were more likely than the reference group to have a request cesarean delivery (odds ratio range, 1.96-2.01), adjusted for health care institutional characteristics. Conclusion: Population-based data confirms the expectancy that request cesarean delivery propensity increases with maternal age. [ABSTRACT FROM AUTHOR]

No previous study has examined the association between paternal race and birth weight among twins.To examine the association of parents'' race and birth weight among twins.Population-based retrospective cohort study to examine the association between parents'' race and birth weight, and its two components, gestation duration and fetal growth among four group of infants: both parents blacks (FB-MB), father white and mother black (FW-MB), father black and mother white (FB-MW), and both parents whites (FW-MW), with “risk-free” analysis to control confounding factors.Twin births (304,466 twins) registered in the United States in 1995–1997.The means of birth weight, gestational age, and birth-weight-for-gestational age z score, and rates of very low birth weight (VLBW, <1500 g), very preterm birth (VPTB, <32 weeks of gestation), and fetal growth restriction (FGR, <10th percentile of z score).Means of birth weight, gestational age, and z score were 2234.0, 2301.9, 2361.1, and 2433.8, and 35.02, 35.24, 35.65, and 35.78, and −0.136, −0.070, −0.039, and 0.063, respectively, and the rates of VLBW, VPTB, and FGR were 14.5, 12.3, 10.5, and 8.1, and 16.0, 13.0, 11.6, and 9.2, and 12.6, 11.1, 10.8, and 8.7, respectively, in the FB-MB, FW-MB, FB-MW, and FW-MW groups. Excluding subjects with various risk factors by risk-free analysis did not change the results.Both parents'' races are important determinants of birth weight, gestational age, and fetal growth among twin pregnancies, with higher effect on gestational age and greater maternal influence than paternal influence. [Copyright &y& Elsevier]

Abstract: Objective: To determine the potential pathway of the association between teenage pregnancy and neonatal and postneonatal mortality. Study Design and setting: We carried out a retrospective cohort study of 4,037,009 nulliparous pregnant women under 25 years old who had a live singleton birth during 1995 to 2000, based on linked birth and infant death data set of the United States. Results: Teenage pregnancy (10–19 years old) was associated with increased neonatal mortality (odds ratio [OR]: 1.20, 95% confidence interval [CI]=1.16–1.24) and postneonatal mortality (OR: 1.47, 95% CI=1.41–1.54) after adjustment for potential confounders. With further adjustment for weight gain during pregnancy, teenage pregnancy was still associated with increased risk of neonatal (OR: 1.23, 95% CI=1.19–1.28) and postneonatal mortality (OR: 1.48, 95% CI=1.42–1.55). When adjustment was made for gestational age at birth, there was no association of teenage pregnancy with neonatal mortality (OR: 0.98, 95% CI=0.95–1.02), whereas there was significant association with postneonatal mortality (OR: 1.40, 95% CI=1.34–1.46). Conclusion: The increased risk of neonatal death associated with teenage pregnancy is largely attributable to higher risk of preterm births, whereas increased postneonatal mortality is independent of the known confounders and gestational age at birth. [Copyright &y& Elsevier]

Abstract: Objective:: To determine an appropriate cutoff value to differentiate physiologic and pathologic birth weight discordance, to determine the prevalence of birth weight discordance ≥25% among twin pregnancies in different sub-populations, and to examine its clinical significance. Study design:: Historical cohort study of 147,262 twin sets registered in the United States between 1995 and 1997. Results:: The prevalence of birth weight discordance ≥25% among twin pregnancies was 8.6%. The prevalence of birth weight discordance ≥25% was significantly decreased with increasing total twin birth weight deciles, was more frequently found in twins with discordant gender (9.1%) than in those twins with concordant gender (8.3%) and in mothers whose age was 30 years or older (9.1%) than those of younger mothers (8.1%). Birth weight discordance ≥25% was associated with earlier gestational age at delivery (35.0 weeks versus 36.0 weeks) and higher neonatal mortality (5.4% versus 2.3%) as compared to twins with lower birth weight discordance. Conclusions:: The prevalence of birth weight discordance ≥25% among twin pregnancies was 8.6%, which is associated with lower gestational age at delivery and higher neonatal mortality rates, and may represent a pathologic process. [Copyright &y& Elsevier]