Maintenance tocolysis with oral micronized progesterone for prevention of preterm birth after arrested preterm labor.

Objective: To evaluate the efficacy of maintenance therapy with oral micronized progesterone (OMP) for prolongation of pregnancy in cases of arrested preterm labor.

Methods: Ninety women at 24-34weeks of singleton pregnancy with intact membranes and arrested preterm labor were randomly allocated to receive OMP (n=45) or placebo (n=45) daily until 37weeks or delivery, whichever was earlier. Outcome parameters were compared using Student t test, χ(2) test, Fisher exact test, and log-rank χ(2) test.

Results: OMP significantly prolonged the latency period (33.29±22.16 vs 23.07±15.42days; P=0.013). Log-rank analysis revealed a significant difference in mean time to delivery between the 2 groups (P=0.014). There were significantly fewer preterm births (33% vs 58%; P=0.034) and low birth weight neonates (37% vs 64%; P=0.017), and significantly higher mean birth weight (2.44±0.58 vs 2.14±0.47kg; P=0.009) in the OMP group. Perinatal outcomes and adverse effects were similar in the 2 groups.

Conclusion: Maintenance tocolysis with OMP significantly prolonged pregnancy and decreased the number of preterm births. Clinical Trial Registry of India: CTRI/2011/10/002043.