Maternal and neonatal outcomes following additional doses of vaginal prostaglandin E2 for induction of labour: a retrospective cohort study

Objective
To assess maternal and neonatal outcomes following the use of additional doses of vaginal prostaglandins (PGE2) above the recommended dose for induction of labour in post-dates pregnancies.

Study design
Retrospective cohort study set in Aberdeen Maternity Hospital, Aberdeen, UK. A total of 3514 nulliparous women with labour induced with vaginal PGE2 (3 mg tablet or 2 mg gel) for a post-dates singleton pregnancy from January 1994 to December 2009 were included. Women receiving ≤ 2 doses of PGE2 were compared with those receiving > 2 doses (maximum 5 doses). Binary logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI). Primary outcomes included mode of delivery, terbutaline use, indication for CS, postpartum haemorrhage, neonatal unit admission, and Apgar score < 7. A further analysis was conducted which stratified for number of doses of PGE2 given.

Results
Of the 3514 women who met inclusion criteria, 605 (17%) received PGE2 that exceeded the licensed dose. They were more likely to deliver by caesarean section (53.4% vs. 31.8%, OR 2.2, 95% CI 1.8–2.6), have a caesarean section for ‘failed’ induction of labour (11.4% vs. 1.9%, OR 4.1, 95% CI 1.3–13.2) or lack of progress in labour (37% vs. 17%, OR 2.8, 95% CI 2.3–3.4), but not for fetal concerns (8.2% vs. 8.8% OR 0.9, 95% CI 0.7–1.3). Terbutaline use and postpartum haemorrhage was no more likely (0.7% vs. 0.9% OR 0.6 95% CI 0.3–1.5 and 19.8% vs. 18.9% OR1.01, 95% CI 0.97–1.06 respectively). Apgar score < 7 (1.1% vs. 1.3% OR 0.9 95% CI 0.8–1.1) and neonatal unit admission (13.7% vs. 10.7% OR 1.2 95% CI 0.8–1.6) were similar in both groups.

Conclusion
The use of additional doses of vaginal PGE2 above the recommended dose for induction of labour was not associated with increased maternal or neonatal morbidity and almost half of these women achieved a vaginal delivery.