Vaginal Progesterone for the Prevention of Preterm Birth in Pregnancies with Short Cervix

To review the literature regarding the efficacy of vaginal progesterone to prevent preterm birth in pregnancies diagnosed with a short cervix, and to provide evidence-based recommendations to delineate the management of these patients.

Multiple randomized trials have attempted to address this clinical question. Most studies are in singleton pregnancies and a few included twin gestations. Studies are heterogeneous in design with different populations, primary outcomes, cervical length thresholds, and vaginal progesterone formulations. Results have been inconsistent, leading to individual-patient data meta-analyses to corroborate previous results. Recently, two trials that evaluated the effect of vaginal progesterone to prevent preterm labor and were included in these meta-analyses have been retracted from publication due to methodological concerns, further complicating the analysis.

Available evidence suggest that the use of daily vaginal micronized progesterone 200 mg or vaginal progesterone gel 90 mg may reduce preterm birth rates in singleton pregnancies with a mid-trimester cervical length < 20 mm regardless of history of obstetrical history. In contrast, the evidence to support the efficacy of vaginal progesterone to reduce preterm births in multifetal gestations with short cervices remain insufficient to support a recommendation for its use.