Recent progesterone trials call for an update of previous syntheses of interventions to prevent preterm birth.
To compare the relative effects of different types and routes of administration of progesterone, cerclage, and pessary at preventing preterm birth in at‐risk women overall and in specific populations.
We searched Medline, EMBASE, CINAHL, Cochrane CENTRAL, and Web of Science up to 1 January 2018.
We included randomised trials of progesterone, cerclage or pessary for preventing preterm birth in at‐risk singleton pregnancies.
Data collection and analysis
We used a piloted data extraction form and performed Bayesian random‐effects network meta‐analyses with 95% credibility intervals (CrI), as well as pairwise meta‐analyses, rating the quality of the evidence using GRADE.
We included 40 trials (11 311 women). In at‐risk women overall, vaginal progesterone reduced preterm birth <34 (OR 0.43, 95% CrI 0.20–0.81) and <37 weeks (OR 0.51, 95% CrI 0.34–0.74), and neonatal death (OR 0.41, 95% CrI 0.20–0.83). In women with a previous preterm birth, vaginal progesterone reduced preterm birth <34 (OR 0.29, 95% CI 0.12–0.68) and <37 weeks (OR 0.43, 95% CrI 0.23–0.74), and 17α‐hydroxyprogesterone caproate reduced preterm birth <37 weeks (OR 0.53, 95% CrI 0.27–0.95) and neonatal death (OR 0.39, 95% CI 0.16–0.95). In women with a short cervix (≤25 mm), vaginal progesterone reduced preterm birth <34 weeks (OR 0.45, 95% CI 0.24–0.84).
Vaginal progesterone was the only intervention with consistent effectiveness for preventing preterm birth in singleton at‐risk pregnancies overall and in those with a previous preterm birth.
In updated NMA, vaginal progesterone consistently reduced PTB in overall at‐risk pregnancies and in women with previous PTB.