- Design
- Systematic review and random-effects meta-analysis of randomised trials
- Population
- 13,644 women with term singleton induction of labour (44 reports)
- Primary outcome
- Vaginal birth within 24 hours
- Effect
- OR 1.48 (95% CI 1.20-1.84); oxytocin OR 0.51 (0.40-0.65); time to birth -230 min
A systematic review and random-effects meta-analysis pooled 44 randomised trial reports of term singleton inductions: 7,040 women given vaginal misoprostol and 6,604 given vaginal dinoprostone.
Misoprostol raised the odds of vaginal birth within 24 hours (OR 1.48, 95% CI 1.20-1.84), though heterogeneity was high. Fewer women needed oxytocin (OR 0.51, 0.40-0.65) and time to birth fell by about 230 minutes (95% CI -286 to -175). Caesarean birth and adverse maternal and neonatal outcomes were comparable. At 25 µg, misoprostol was similarly effective with less uterine hyperstimulation with fetal heart rate changes.
Dinoprostone remains the default induction agent in many units. This review supports low-dose vaginal misoprostol as at least as safe and more effective, and it is far cheaper.
In Indian practice, where dinoprostone gel needs cold storage and costs more, misoprostol is already widely used; this supports using the 25 µg dose rather than higher ones.
- Review your induction protocol: is dinoprostone first-line by habit or by evidence?
- Use 25 µg vaginal misoprostol rather than 50 µg or more to limit hyperstimulation.
- Keep continuous fetal monitoring available after each dose, as with any prostaglandin.
- Misoprostol is not appropriate after a previous caesarean or uterine surgery.
Why it matters
The cheaper agent is also the more effective one, which puts the burden of justification on units still using dinoprostone first.
Don't overread it
Heterogeneity in the primary outcome was high, and the evidence is from term singleton inductions; it does not support misoprostol for a scarred uterus.
The statistics, in plain English
An odds ratio of 1.48 means higher odds of vaginal birth within 24 hours, not a 48% higher rate; when the outcome is common, odds ratios overstate the relative difference. High heterogeneity means trials disagreed on the size of the benefit, though nearly all pointed the same way.
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