Progestogens as Maintenance Treatment in Arrested Preterm Labor: A Systematic Review and Meta-analysis

To evaluate the efficacy of maintenance tocolysis with progestogens compared with placebo or no treatment in women with singleton pregnancies and arrested preterm labor.

Studies without language restrictions were identified from MEDLINE, EMBASE, PubMed, Scopus, the Cochrane Pregnancy and Childbirth Group's Trials Register, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov from inception to June 2015. MeSH headings for progestogens were combined with terms regarding labor, tocolysis, or preterm birth. Reference lists of included studies and GoogleSearch were also reviewed.

Randomized controlled trials that compared progestogens as a maintenance treatment after arrested preterm labor in singleton pregnancies with placebo or no treatment were identified. Selected studies evaluated delivery before 37 or 34 weeks of gestation or the latency period from randomization to delivery. Excluded studies used progestogens as prevention in asymptomatic women at risk. Risk of bias assessment, subgroup analysis on type of progestogens used, and sensitivity analysis by high-quality studies were performed.

Sixteen randomized controlled trials consisting of 1,917 participants were included. Study characteristics and quality were recorded. Preterm delivery at less than 37 weeks of gestation was decreased (38.2% compared with 44.3%; relative risk 0.79, 95% confidence interval [CI] 0.65-0.97) and pregnancy was prolonged (mean difference 8.1 days; 95% CI 3.8-12.4) when women treated with progestogens were compared with placebo or no treatment. There were no differences in the outcome of delivery at less than 34 weeks of gestation (15.6% compared with 18.3%; relative risk 0.77, 95% CI 0.53-1.12). However, sensitivity analysis including five high-quality studies showed no significant differences for preterm delivery at less than 37 weeks of gestation (37.2% compared with 36.9%; relative risk 0.91, 95% CI 0.67-1.25) or latency period (mean difference 0.6 days; 95% CI -3.7 to 4.9).

There is insufficient high-quality data to inform clinicians and patients about the use of progestogens as maintenance treatment after arrested preterm labor to reduce the incidence of preterm birth or pregnancy prolongation.