Contribution of method of conception on pregnancy outcome after the 11-13 weeks scan.

OBJECTIVE To examine the effect of method of conception on adverse pregnancy outcome after the 11-13 weeks scan. METHODS Prospective screening study for adverse obstetric outcomes in women with singleton pregnancies and live fetus with no obvious defects at 11(+0)-13(+6) weeks. The method of conception was recorded as spontaneous, in vitro fertilization (IVF) and assisted by ovulation induction (OI) drugs without IVF. Regression analysis was performed to examine the association between the method of conception and pregnancy outcome after adjustment for maternal characteristics. RESULTS In the study population of 41,577 pregnancies, conception was spontaneous in 40,261 (96.9%), by IVF in 634 (1.5%) and by OI in 682 (1.6%). In the pregnancies conceived by assisted reproductive technology, compared to spontaneous conceptions, there was a higher risk of stillbirth, pre-eclampsia, gestational hypertension, gestational diabetes mellitus, delivery of small for gestational age neonates and caesarean section. However, multiple regression analysis showed that after taking into account maternal characteristics, the only significant contributions of IVF were for pre-eclampsia and elective caesarean section and the contributions of OI were for miscarriage, spontaneous early preterm delivery and small for gestational age. CONCLUSIONS Conception by IVF and OI is associated with increased risk for adverse pregnancy outcome.