Induction of labor with Foley catheter and risk of subsequent preterm birth: follow‐up study of two randomized controlled trials ( <scp>PROBAAT</scp> ‐1 and ‐2)

Objective To evaluate the rate of preterm birth (PTB) in a subsequent pregnancy in women who had undergone term induction using a Foley catheter compared with prostaglandins. Methods This was a follow‐up study of two large randomized controlled trials (PROBAAT‐1 and PROBAAT‐2). In the original trials, women with a term singleton pregnancy with the fetus in cephalic presentation and with an indication for labor induction were randomized to receive either a 30‐mL Foley catheter or prostaglandins (vaginal prostaglandin E2 in PROBAAT‐1 and oral misoprostol in PROBAAT‐2). Data on subsequent ongoing pregnancies > 16 weeks’ gestation were collected from hospital charts from clinics participating in this follow‐up study. The main outcome measure was preterm birth 16 weeks' gestation in the Foley catheter and prostaglandin groups, respectively. There were no differences in baseline characteristics between the groups. The overall rate of PTB in a subsequent pregnancy was 9/251 (3.6%) in the Foley catheter group vs 10/258 (3.9%) in the prostaglandin group (relative risk (RR), 0.93; 95% CI, 0.38–2.24), and the rate of spontaneous PTB was 5/251 (2.0%) vs 5/258 (1.9%) (RR, 1.03; 95% CI, 0.30–3.51). Conclusion In women with term singleton pregnancy, induction of labor using a 30‐mL Foley catheter is not associated with an increased risk of PTB in a subsequent pregnancy, as compared to induction of labor using prostaglandins. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.