A new study has identified a significant additional risk of stillbirth when pregnancies continue to 41 weeks compared to delivery at 40 weeks.
Researchers examined data from 13 studies providing data on 15 million pregnancies, including 17,830 stillbirths and 2,348 neonatal deaths, to quantify the risks of stillbirth and neonatal death at term according to gestational age.
They found the prospective risk of stillbirth increased with gestational age from 0.11 per 1,000 pregnancies at 37 weeks (95% CI 0.07 to 0.15) to 3.18 per 1,000 at 42 weeks (95% CI 1.84 to 4.35). One additional stillbirth occurred for every 1,449 pregnancies that advanced from 40 to 41 weeks.
Neonatal mortality remained steady in infants born from 38 to 41 weeks; however, it increased when pregnancies continued beyond 41 weeks, and was significantly higher for deliveries at 42 weeks compared with 41 weeks gestation (risk ratio [RR] 1.87, 95% CI 1.07 to 2.86, P = .012).
Writing in PLOS Medicine, the authors said “any discussion with women considering prolonging their pregnancy beyond 41 weeks gestation should include information on the absolute risk increase, and the effects of induction of labour on mode of delivery and perinatal outcomes.”