Perinatal morbidity and mortality in twin pregnancies with dichorionic placentas following assisted reproductive techniques or ovarian induction alone: a comparative study.

ABSTRACT

OBJECTIVE: To compare maternal and perinatal outcome in non-spontaneously and spontaneously conceived dichorionic twin pregnancies. STUDY DESIGN: We report a retrospective study of all 350 twin pregnancies delivered ≥22 weeks of gestation between January 1, 2001 and December 31, 2005 in a tertiary maternity unit. We compared maternal outcome, perinatal morbidity and neonatal mortality between spontaneous and non-spontaneous dichorionic twin pregnancies, with a subgroup analysis separating pregnancies following assisted reproduction technology (ART group) from those following ovarian induction alone (OI group). Generalized linear model and multivariate analysis were performed. RESULTS: The proportion of primiparous women and the mean maternal age were higher in the non-spontaneously conceived dichorionic twin pregnancy group as expected (70.2% vs. 38.2%, p<0.001 and 32.1 ± 3.8 vs. 30.7 ± 4.6 years, p<0.01). Multivariate analysis, adjusted for maternal age and parity, revealed that non-spontaneously conceived dichorionic twin pregnancies were associated with a higher risk of very preterm birth (OR 2.20, 95% confidence interval 1.02-4.77, p<0.05), low birth weight (1.77, 1.21-2.61, p<0.01), very low birth weight (1.99, 1.13-3.49, p<0.05), NICU admission (1.66, 1.14-2.43, p<0.01), and fetal or neonatal death (3.21, 1.30-7.95, p<0.05). Multivariate analysis confirmed that the mean gestational age (p<0.01) and mean birth weight of the first (p<0.05) and second twins (p<0.01) were lower in the non-spontaneously conceived dichorionic twin pregnancy group. These associations were confirmed in the OI group analysis (n=39) but not in the ART group (n=65). Ovarian induction was associated with an increase in the risk of preterm and very preterm births (2.25, 1.06-4.75, p<0.05 and 3.47, 1.42-8.49, p<0.01, respectively), low and very low birth weights (2.87, 1.63-5.05, p<0.001 and 2.59, 1.33-5.07, p<0.01, respectively), NICU admission (2.92, 1.67-5.11, p<0.001) and fetal or neonatal death (4.20, 1.40-12.56, p<0.05). The mean gestational age (p<0.001) and mean birth weight of the first (p<0.01) and second twins (p<0.001) were also lower in the OI group. CONCLUSIONS: Twin pregnancies with dichorionic placentation following non-spontaneously conceived pregnancy are associated with a higher risk of adverse perinatal outcome compared with dichorionic spontaneously conceived twin pregnancies especially in case of ovarian induction alone.