Improved neonatal outcome after active management of prolonged pregnancies beyond 41 +2 weeks in nulliparous, but not among multiparous women

Prolonged pregnancies are associated with adverse maternal and fetal outcome. In Sweden, no national guidelines exist for when to induce prolonged pregnancies. Material and methods Singleton cephalic prolonged pregnancies (defined as ≥ 41 +3 gestational weeks) during 2001–2013 ( n  = 199 770) were identified using the Swedish Medical Birth Register. The maternity units were divided into three groups (tertiles) based on the proportion of pregnancies ≥ 42 +3 gestational weeks among all pregnancies ≥ 41 +3  weeks. The pregnancy outcome among women delivered at the units with the most expectant management of prolonged pregnancies (> 17.6% proceeding to 42 +3  weeks), was compared with that among women delivered at units with the most active management (< 12.6% proceeding to 42 +3  weeks). Odds ratios ( OR ) were calculated using simple and multiple logistic regression. Adjustments were made for year of delivery, hospital level, maternal age, body mass index, and smoking. Results Among primiparas, an increased risk of Apgar score < 7 at 5 minutes [odds ratio ( OR ) 1.27, 95% CI 1.16–1.41] and meconium aspiration ( OR 1.49, 95% CI 1.14–1.95) was found after birth at most expectant units compared with most active units, but among multiparas, no such associations were detected. A decreased rate of cesarean section was found for both primiparas ( OR 0.83, 95% CI 0.80–0.86) and multiparas ( OR 0.82, 95% CI 0.77–0.86) at units with expectant vs. active management. No association between perinatal death and delivery‐unit specific management of prolonged pregnancies was detected. Conclusions Offspring to primiparas might gain from a more active management of prolonged pregnancies, whereas no such improvement of neonatal outcome among multiparous women was detected.