Outcome of two sequential singleton pregnancies and twin pregnancies among primiparous women at advanced age undergoing IVF

Purpose: To compare the obstetrical and detailed neonatal outcomes of primipara of advanced maternal age conceiving two sequential singleton pregnancies by IVF with those of primipara conceiving twins by IVF. Methods: A retrospective study of all primiparous women aged ≤ 38 years and conceived by IVF who delivered sequential singletons or delivered twins at a single tertiary university affiliated medical center between 2011 and 2019. We performed two main comparisons: 1. First vs. second singleton pregnancies. 2. Two singleton pregnancies vs. twin pregnancies. Results: Overall, there were 63 women with consecutive singleton IVF pregnancies. The median age was 40.0 at first pregnancy and 42.0 in the second pregnancy. Pregnancy and delivery complications rates did not differ significantly between the first and the second singleton pregnancies, including gestational hypertensive disorders (7 (11.1%) vs. 4 (6.3%), p = 0.530), gestational diabetes mellitus (13 (20.6%) vs 18 (28.5%), p = 0.410), intrauterine growth restriction (6 (9.5%) vs. 4 (6.3%), p = 0.744), or cesarean delivery (25 (39.7%) vs. 29 (46%), p = 0.589). Rates of delivery before 32 weeks gestation were similar for both first and second singleton pregnancies (1.6%, p > 0.999). The proportion of neonatal adverse outcome in both first and second singleton pregnancies groups was low and did not differ between the groups. Compared with women who delivered sequential singletons, women with twin pregnancies had significantly higher cesarean delivery rates (113 (83.7%) vs. 29 (46%), p < 0.001) and lower gestational ages at delivery (36.2 vs. 38.4, p < 0.001) than women with two singleton deliveries. Adverse neonatal outcomes were significantly higher for twin pregnancies, including birthweight < 1500 g (17 (12.6%) vs. 2 (3.2%), p = 0.036), neonatal intensive care unit admission (57 (42.2%) vs. 4 (6.3%), p < 0.001), neonatal hypoglycemia (23 (17%) vs. 3 (4.8%), p = 0.017), and respiratory distress syndrome (14 (10.4%) vs. 1 (1.6%), p = 0.040). Length of neonatal hospitalization was significantly longer for twins (9 vs. 5 days, p < 0.001). The rate of gestational hypertensive disorders (preeclampsia and gestational hypertension) was similar between the groups, but the rates of severe preeclampsia trended higher among women who carried twins (8 (5.9%) vs. 0, p = 0.057). Conclusions: Sequential singleton pregnancies at primipara women of advanced maternal age have an overall very good outcome, with no clinically significant difference between the pregnancies. In addition, their outcome is much better compared with twins.