BACKGROUND: Recent progesterone trials call for an update of previous syntheses of interventions to prevent preterm birth.
OBJECTIVES: 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.
SEARCH STRATEGY: We searched Medline, EMBASE, CINAHL, Cochrane CENTRAL, and Web of Science up to 1 January 2018.
SELECTION CRITERIA: 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.
MAIN RESULTS: 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).
CONCLUSIONS: 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.
TWEETABLE ABSTRACT: In updated NMA, vaginal progesterone consistently reduced PTB in overall at-risk pregnancies and in women with previous PTB.