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

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.