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Fetal, neonatal and maternal sequelae of birth weight and sex discordance among twin gestations Jahanfar, Shayesteh


Birth weight discordance and sex discordance are two major predictors in identifying adverse fetal, neonatal and maternal outcomes in twin gestation. No study to date has comprehensively studied the role of these predictors together and in relation to placenta and cord. We analysed data from a large population-based sample of 10 years twin deliveries born in British Columbia and compared the result with a hospital-based sub-sample, taking chorionicity information into account. The unique aspect of our study is the use of a large population-based sample, generalized equation modeling, a wide range of confounding variables and analysing chorionicity and pathological aspects of placenta and cord in relation to growth and sex discordance. Aberrant growth among twins was related to unequal placenta sharing, existence of anastomosis between superficial vessels on the placental surface, length of umbilical cord and type of cord insertion. Fetal sex is an important predictor in placental findings including anastomosis, unequal placenta sharing, placental lesions and placental inflammation. Receiver operating characteristic analysis revealed that a threshold level of ≥30% had the optimal accuracy to detect perinatal mortality irrespective of chorionicity. Perinatal mortality and morbidity were also associated with growth and sex discordance. Early and late neonatal mortality were more likely in male infants from male-female twin pairs compared with females from female-female pairs. The predictive basis of growth discordance on stillbirth was dependent on fetal sex discordance, fetal growth, parity, gestational age and sizes of the twins. Higher odds of adverse maternal outcomes were found for mothers carrying discordant growth twins compared to the reference category for the following conditions: preeclampsia, pregnancy induced hypertension, preterm labor, premature rupture of membrane, prolonged preterm rupture of membrane, length of stay >3 days and cesarean section. Sex pairing is associated with postpartum length of stay >3 days, proteinuria, pregnancy induced hypertension, preeclampsia and cesarean section. Given that chorionicity information is not available in most datasets, it is reasonable to use sex discordance as a proxy measure. Twin pregnancies can benefit from reliance of clinicians on these data showing the importance of growth and sex discordance in prediction of adverse pregnancy outcomes.

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