The role of vaginal progesterone in established pre-term labor: A randomized controlled trial

Pre-term birth (PTB) is the leading cause of mortality and morbidity in newborn and infants. One of the proposed theories is the withdrawal of progesterone, either actual or functional, to be an antecedent to the onset of labor. The aim of the study is to evaluate the role of vaginal progesterone in delaying delivery following an episode of arrested pre-term labor.

This is a pragmatic open-label randomized controlled trial that was conducted in the Department of Obstetrics and Gynecology at All India Institute of Medical Sciences, Jodhpur. Hundred patients with singleton pregnancies presenting with pre-term labor between 24 and 34 weeks of gestation and treated successfully with acute tocolysis for 48 hours and steroids covered were randomized to receive either progesterone 400 mg vaginal suppository or no treatment.

The primary outcome was the duration of randomization to delivery interval, which was significantly higher in the study than in the control group (28 days versus 10 days). The secondary outcomes such as gestational age at delivery was also higher in the study group compared to the control group (82% versus 60% delivered after 37 weeks in the study group and control group, respectively). The neo-natal outcomes such as birth weight (2802 grams versus 2324 grams), incidence of respiratory distress syndrome (RDS) (13% versus 26%), and newborn intensive care unit (NICU) admission (17% versus 31%) were lower in the study group, which signifies decreased neo-natal morbidities and mortalities in pre-term labor treated with maintenance tocolysis in the form of vaginal progesterone.

Administration of vaginal progesterone (400 mg, daily) following an episode of arrested pre-term labor significantly increased the duration to delivery interval; that is, it reduced the rate of PTB before 37, 32, and 28 weeks of gestation among women. It further reduced the neo-natal morbidities such as RDS and NICU admission and increased the birth weight among infants of women assigned to progesterone treatment.