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 < 37 weeks’ gestation in a subsequent pregnancy. Results: Fourteen hospitals agreed to participate in this follow-up study. Of the 1142 eligible women, 572 had been allocated to induction of labor using a Foley catheter and 570 to induction of labor using prostaglandins. Of these, 162 (14%) were lost to follow-up. In total, 251 and 258 women had a known subsequent pregnancy > 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.
Bibliographical noteFunding Information:
We thank all the women who participated in the PROBAAT trials and all participating institutions and their staff for their contribution to this follow-up study. The original PROBAAT-2 trial was funded by FondsNutsOhra. For the PROBAAT-1 trial and this follow-up study, no funding was received. M.V. received a doctoral grant for teachers by The Netherlands Organisation for Scientific Research (023.011.051). B.M. is supported by a NHMRC Practitioner Fellowship (GNT1082548). Funding sources had no role in design, execution, analyses, interpretation or decision to submit results. B.M. reports consultancy for ObsEva, Merck KGaA and Guerbet.
The original PROBAAT‐2 trial was funded by FondsNutsOhra. For the PROBAAT‐1 trial and this follow‐up study, no funding was received. M.V. received a doctoral grant for teachers by The Netherlands Organisation for Scientific Research (023.011.051). B.M. is supported by a NHMRC Practitioner Fellowship (GNT1082548). Funding sources had no role in design, execution, analyses, interpretation or decision to submit results.
© 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.