Vaginal progesterone gel reduces rate of preterm birth

Vaginal progesterone administered from the mid-trimester of pregnancy until term in women with a premature cervical shortening, as confirmed by transvaginal ultrasound, significantly reduced the rate of preterm birth before 33 weeks gestation, according to a phase 3 study published online in Ultrasound in Obstetrics & Gynecology.

Investigators conducted a multicenter, double-blind, placebo-controlled study that enrolled 458 asymptomatic women with a singleton pregnancy and a short cervix. Patients were randomly assigned to receive either vaginal progesterone gel or placebo vaginal gel once daily from 20 to 24 weeks gestation until 37 weeks gestation, rupture of membranes, or delivery, whichever occurred first. Women self-administered the progesterone gel study drug once daily in the morning.

Use of vaginal progesterone gel was associated with a 45% reduction in the rate of preterm birth before 33 weeks of gestation (P=.020) and improved neonatal outcomes. A reduction in the risk of preterm birth was observed in both women with and without a history of preterm birth. The study also demonstrated that self-administered progesterone gel was associated with a significant reduction in the risk of preterm birth before 28 weeks and 35 weeks of gestation (P=.036 and P=.016, respectively).

Adverse events were comparable between women who received vaginal progesterone gel and those who received placebo. The most frequently reported adverse events related to study treatment occurred in 2% of women and included vaginal pruritus, vaginal discharge, vaginal candidiasis, and nausea.

"The prevention of preterm birth is a major healthcare priority, and there are currently limited interventions available," said Roberto Romero, MD, the principal investigator of the study. Romero is chief of the Perinatology Research Branch of the National Institute of Child Health and Human Development/the National Institutes of Health. "Our data are the first to demonstrate that an intervention can dramatically reduce the rate of early preterm birth (<33 weeks of gestation) and improve neonatal outcome. This was accomplished with vaginal progesterone without any evidence of a safety signal."

Several authors disclosed financial and advisory relationships with Columbia Laboratories.