The influence of various induction methods on adverse outcomes in small for gestational age neonates: A secondary analysis of the PROBAAT 1 and 2 trials

Objective: To evaluate the safety aspects of different induction methods in pregnancies with small-for-gestational-age neonates. Study design: This was a secondary analysis of two previously reported multicenter, randomized controlled trials conducted in the Netherlands. In the original trials, women were randomized to either a 30 cc Foley catheter, vaginal prostaglandin E2 (PROBAAT-1) or oral misoprostol (PROBAAT-2). A total of 425 patients with a term, singleton pregnancy in cephalic presentation with an indication for labor induction and a small-for-gestational-age neonate were included in this secondary analysis. Our primary outcome was a composed adverse neonatal outcome of Apgar score < 7 after 5 min and/or a pH in the umbilical artery < 7.05 and/or NICU admission. Secondary outcomes were mode of birth, operative birth for fetal distress and pH < 7.10 in the umbilical artery. For these outcome measures, multivariate as well as bivariate analyses were performed. Results: An adverse neonatal outcome occurred in 4.7 % (10/214) induction with a Foley catheter, versus 12.8 % (19/149) after misoprostol (RR 0.36; 95 % CI 0.17–0.76) and 4.7 % (3/64) after Prostaglandin E2 (RR 0.98; 95 %CI 0.28–3.51). For individual components of the composed outcome of adverse events, a difference was found between a Foley catheter and misoprostol for Apgar score < 7 at 5 min (0.5 % versus 3.4; RR 0.14; 95 %CI 0.02–1.16) and NICU admission (1.9 % versus 6.1 %; RR 0.31; 0.10–0.97). No differences were found for mode of birth. Conclusions: For women who gave birth to a small-for-gestational-age neonate, a Foley catheter is probably a safer induction method compared to oral misoprostol.