Obstetric and Perinatal Outcomes following Ovulation Induction and Unassisted Pregnancies in the Same Mother

Objective We aimed to assess whether ovulation induction treatments affect obstetric and neonatal outcomes. Study Design This was a historic cohort study of deliveries in a single university-affiliated medical center between November 2008 and January 2020. We included women who had one pregnancy following ovulation induction and one unassisted pregnancy. The obstetric and perinatal outcomes were compared between pregnancies following ovulation induction and unassisted pregnancies, so that each woman served as her own control. The primary outcome measure was birth weight. Results A total of 193 deliveries following ovulation induction and 193 deliveries after unassisted conception by the same women were compared. Ovulation induction pregnancies were characterized by a significantly younger maternal age and a higher rate of nulliparity (62.7 vs. 8.3%, p < 0.001). In pregnancies achieved by ovulation induction, we found a higher rate of preterm birth (8.3 vs. 4.1%, p = 0.02) and instrumental deliveries (8.8 vs. 2.1%, p = 0.005), while cesarean delivery rates were higher following unassisted pregnancies. Birth weight was significantly lower in ovulation induction pregnancies (3,167 ± 436 vs. 3,251 ± 460 g, p = 0.009), although the rate of small for gestational age neonates was similar between the groups. On multivariate analysis, birth weight remained significantly associated with ovulation induction after adjustment for confounders, while preterm birth did not. Conclusion Pregnancies following ovulation induction treatments are associated with lower birth weight. This may be related to an altered placentation process following uterine exposure to supraphysiological hormonal levels.