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Introduction: Our study aim was to evaluate standard ultrasound-derived fetal biometric parameters in the prediction of clinically significant intertwin birthweight discordance defined as ≥18%., Material and Methods: This was a secondary analysis of a prospective cohort study of 1028 unselected twin pairs recruited over a two-year period. Dichorionic twins underwent two-weekly ultrasonographic surveillance from 24 weeks' gestation, with surveillance of monochorionic twins two-weekly from 16 weeks. Ultrasonographic biometric data from 24 to 36 weeks were evaluated for the prediction of an intertwin birthweight discordance threshold ≥18%. Umbilical artery Doppler waveform data was also analyzed to evaluate whether it was predictive of birthweight discordance., Results: Of the 956 twin pairs analyzed for discordance, 208 pairs were found to have a clinically significant birthweight discordance ≥18%. All biometric parameters were predictive of significant inter-twin birthweight discordance at low cut-offs, with low discriminatory powers when ROC curves were analyzed. Discordance in estimated fetal weight was predictive of a significant birthweight discordance at all gestational categories with cut-offs between 8 and 11%. A low-discriminatory power and poor sensitivity and specificity were also observed. An abnormal umbilical artery Doppler was predictive of birthweight discordance ≥18% between 28 and 32 weeks' gestation, although with poor sensitivity and specificity., Conclusions: Calculation of estimated fetal weight and birthweight discordance between twins allows minimal margin for error. These margins make it difficult to accurately predict those who are at or above the discordance threshold of 18%. These findings highlight that small intertwin discrepancies in weight and biometry should not be overlooked and merit further investigation., (© 2017 Nordic Federation of Societies of Obstetrics and Gynecology.)

Objective: Gestational hypertensive disease (GHD) is associated with pregnancy-related complications and poor maternal and fetal outcomes in singleton pregnancies. We sought to examine the influence of GHD in a large prospective cohort of twin pregnancies., Study Design: The ESPRIT study was a national multicenter observational cohort study of 1028 structurally normal twin pregnancies. Each pregnancy underwent sonographic surveillance with two-week ultrasound from 24 weeks for dichorionic and from 16 weeks for monochorionic gestations. Characteristics and demographics as well as labour and delivery outcome data were prospectively recorded. Perinatal mortality, admission to the neonatal intensive care unit (NICU) and a composite of morbidity of respiratory distress syndrome, hypoxic ischaemic encephalopathy, periventricular leukomalacia, necrotising enterocolitis and sepsis were documented for all cases. Outcomes for patients with documented GHD (pre-eclampsia and gestational hypertension) were compared with those without GHD., Results: Perinatal outcome data were recorded for 977 patients. Women with GHD had a higher body mass index (27.1 ± 6.4 vs 25.2 ± 4.5, P < 0.0001) than those without and were more likely to be nulliparous (65% (59/92) vs 46% (407/885), P = 0.001). Both groups had similar mean birthweights, but those with GHD were more likely to have a birthweight discordance ≥18% (35% (32/92) vs 20% (179/885), P = 0.001). Rates of caesarean delivery were higher in those twin pregnancies affected by GHD, and while the rate of composite morbidity was similar in both groups, twins in the GHD group had higher rates of NICU admission., Conclusion: In twin gestations, gestational hypertension independently confers an increased risk for emergency caesarean delivery, birthweight discordance and NICU admission, such that intensive maternal-fetal monitoring is justified when hypertension develops in a twin pregnancy., (© 2016 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.)

Objective: We sought to evaluate the association between placental histological abnormalities and birthweight discordance and growth restriction in twin pregnancies., Study Design: We performed a multicenter, prospective study of twin pregnancies. Placentas were examined for evidence of infarction, retroplacental hemorrhage, chorangioma, subchorial fibrin, or abnormal villus maturation. Association of placental lesions with chorionicity, birthweight discordance, and growth restriction were assessed., Results: In all, 668 twin pairs were studied, 21.1% monochorionic and 78.9% dichorionic. Histological abnormalities were more frequent in placentas of smaller twins of birthweight discordant pairs (P = .02) and in placentas of small for gestational age infants (P = .0001) when compared to controls. The association of placental abnormalities with both birthweight discordance and small for gestational age was significant for dichorionic twins (P = .01 and .0001, respectively). No such association was seen in monochorionic twins., Conclusion: In a large, prospective, multicenter study, we observed a strong relationship between abnormalities of placental histology and birthweight discordance and growth restriction in dichorionic, but not monochorionic, twin pregnancies., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Objective: The purpose of this study was to evaluate the impact of noncentral placental cord insertion on birthweight discordance in twins., Study Design: We performed a multicenter, prospective trial of twin pregnancies. Placental cord insertion was documented as central, marginal, or velamentous according to a defined protocol. Association of the placental cord insertion site with chorionicity, birthweight discordance, and growth restriction were assessed., Results: Eight hundred sixteen twin pairs were evaluated; 165 pairs were monochorionic, and 651 pairs were dichorionic. Monochorionic twins had higher rates of marginal (P = .0068) and velamentous (P < .0001) placental cord insertion. Noncentral placental cord insertion was more frequent in smaller twins of discordant pairs than control pairs (29.8% vs 19.1%; P = .004). Velamentous placental cord insertion in monochorionic twins was associated significantly with birthweight discordance (odds ratio, 3.5; 95% confidence interval, 1.3-9.4) and growth restriction (odds ratio, 4; 95% confidence interval, 1.1-14.3)., Conclusion: Noncentral placental cord insertion contributes to birthweight discordance in monochorionic twin pregnancies. Sonographic delineation of placental cord insertion may be of value in antenatal assessment of twin pregnancies., (Copyright © 2011 Mosby, Inc. All rights reserved.)

Objective: To establish the level of birth weight discordance at which perinatal morbidity increases in monochorionic and dichorionic twin pregnancy., Methods: This prospective multicenter cohort study included 1,028 unselected twin pairs recruited over a 2-year period. Participants underwent two weekly ultrasonographic surveillance from 24 weeks of gestation with surveillance of monochorionic twins two-weekly from 16 weeks. Analysis using Cox proportional hazards compared a composite measure of perinatal morbidity (including any of the following: mortality, respiratory distress syndrome, hypoxic-ischemic encephalopathy, periventricular leukomalacia, necrotizing enterocolitis, or sepsis) at different degrees of birth weight discordance with adjustment for chorionicity, gestational age, twin-twin transfusion syndrome, birth order, gender, and growth restriction., Results: Perinatal outcome data were recorded for 977 patients (100%) who continued the study with both fetuses alive beyond 24 weeks, including 14 cases of twin-twin transfusion syndrome. Adjusting for gestation at delivery, twin order, gender, and growth restriction, perinatal mortality, individual morbidity, and composite perinatal morbidity were all seen to increase with birth weight discordance exceeding 18% for dichorionic pairs (hazard ratio 2.2, 95% confidence interval [CI] 1.6-2.9, P<.001) and 18% for monochorionic twins without twin-twin transfusion syndrome (hazard ratio 2.6, 95% CI 1.6-4.3, P<.001). A minimum twofold increase in risk of perinatal morbidity persisted even when both twin birth weights were appropriate for gestational age., Conclusion: : The threshold for birth weight discordance established by this prospective study is 18% both for dichorionic twin pairs and for monochorionic twins without twin-twin transfusion syndrome. This threshold is considerably lower than that defined by many retrospective series as pathologic. We suggest that an anticipated difference of 18% in birth weight should prompt more intensive fetal monitoring.