Original Research|Articles in Press, 100896

Booster course of antenatal corticosteroids after preterm prelabor rupture of membranes, double-blind randomized trial

Published:February 13, 2023DOI:



      Preterm prelabor rupture of membranes is a leading cause of preterm birth and is responsible for 18-20% of perinatal deaths in this country. An initial course of antenatal corticosteroids has been shown to reduce morbidity and mortality in preterm prelabor rupture of membranes. For patients who remain undelivered 7 days or more after initial course of antenatal corticosteroids, it is uncertain whether a booster course of antenatal corticosteroids reduces neonatal morbidity or increases infection risk. ACOG has concluded that evidence is insufficient to make a recommendation.


      Our objective was to test whether a single booster course of antenatal corticosteroids improves neonatal outcomes after preterm prelabor rupture of membranes.

      Study Design

      We conducted a multicenter, placebo-controlled randomized clinical trial. Inclusion criteria were: preterm prelabor rupture of membranes, gestational age 24.0-32.9 weeks, singleton, initial antenatal corticosteroid course at least 7 days before randomization, planned expectant management. Consenting patients were randomized in gestational age blocks to booster antenatal corticosteroids (betamethasone 12 mg q24h x 2) or saline placebo. The primary outcome was composite neonatal morbidity or death. A sample size of 194 patients was calculated to yield 80% power at P<0.05 to detect reduction of primary outcome from 60% in placebo group to 40% in antenatal corticosteroids group.


      From April 2016 through August 2022, 194 patients consented and were randomized (47% of 411 eligible). Intent-to-treat analysis was performed on 192 patients (two placebo patients left hospital, outcomes unknown). The groups had similar baseline characteristics. The primary outcome occurred in 64% with booster antenatal corticosteroids vs 66% with placebo (odds ratio 0.82, 95% CI 0.43-1.57, gestational age-stratified Cochran-Mantel-Haenszel test). Individual components of the primary outcome and secondary neonatal and maternal outcomes were not significantly different between antenatal corticosteroids and placebo groups. Specifically, chorioamnionitis (22% vs 20%, respectively), postpartum endometritis (1% vs 2%), wound infections (2% vs 0%), and proven neonatal sepsis (5% vs 3%) were not different between groups.


      A booster course of antenatal corticosteroids at least 7 days after the first antenatal corticosteroids course in preterm prelabor rupture of membranes patients did not improve neonatal morbidity or any other outcome in this adequately-powered, double-blind randomized clinical trial.  Booster antenatal corticosteroids did not increase maternal or neonatal infection.


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