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Lack of evidence that vaginal progesterone prevents recurrent preterm birth
Clinical Question
Does vaginal progesterone prevent recurrent preterm birth in women with a history of spontaneous preterm birth?
Bottom line
This paper documents that although a simple meta-analysis of 10 randomized controlled trials supports vaginal progesterone as efficacious treatment to prevent recurrent preterm birth at less than 37 weeks' and less than 34 weeks' gestation, it is due to the outsized effect of small studies of low quality. Three large studies consistently showed no effect. This calls into question current American College of Obstetricians and Gynecologists (ACOG) guidelines that recommend vaginal progesterone for this indication. This meta-analysis did not address the treatment with vaginal progesterone for women with shortened cervix, which current ACOG guidelines also support. 1a-
Reference
Study design: Meta-analysis (randomized controlled trials)
Funding: Government
Setting: Various (meta-analysis)
Synopsis
The authors of this meta-analysis identified 10 randomized controlled trials with 2958 participants addressing vaginal progesterone versus placebo or no treatment to prevent recurrent preterm birth among asymptomatic women with singleton pregnancy and a history of at least one spontaneous preterm birth. The authors did not include studies with the primary aim to prevent preterm birth based on mid-trimester ultrasonographic finding of shortened cervix or threatened preterm labor. Progesterone treatment began at 20 to 24 weeks' gestation and continued until 37 completed weeks. The dosing range was from 90 mg to 400 mg daily. There were 7 small (< 150 participants) and 3 large (> 600 participants) studies. All but one of the small studies had features of high risk (or some concern for) risk of bias, and all were conducted in low- or middle-income countries. The 3 large studies were all at low risk of bias. The authors explained multiple issues regarding the validity of the small studies, including a pronounced asymmetry of funnel plot. The meta-analysis of the results for prevention of preterm birth at less than 37 weeks' and less than 34 weeks' gestation were statistically significant. However, a planned subgroup analysis of high-quality studies, including the 3 large studies and 1 small study, showed there was no effect for birth at less than 37 weeks (relative risk [RR] 0.98; 95% CI 0.88 - 1.09) or birth at less than 34 weeks (RR 0.94; 0.78 - 1.13). There were no unexpected significant differences in multiple other analyses of secondary maternal and infant outcomes, and none related to the daily progesterone dose. The conclusions from this rigorous analysis differ from those of the EPPPIC Group's 2021 systematic review.
Reviewer
Linda Speer, MD
Professor and Chair, Department of Family Medicine
University of Toledo
Toledo, OH
Comments
Vaginal Progesterone not proven effective in preventing pret
This meta analysis shows no real proof that the common practice time of vaginal progesterone is effective in preventing preterm labour.
VAGINAL PROGESTERONE TO PREVENT PRETERM PREGNANCY
NO GOOD EVIDENCE OF REDUCED PT LABOUR