The following is a summary of “Vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in twin gestations: a systematic review and meta-analysis,” published in the DECEMBER 2023 issue of Obstetrics and Gynecology by Conde-Agudelo, et al.

For a study, researchers sought to assess the effectiveness of vaginal progesterone in preventing preterm birth and associated adverse perinatal outcomes in pregnancies involving twins.

The research was based on data extracted from databases such as MEDLINE, Embase, LILACS, and CINAHL, spanning from their inception to January 31, 2023. Additionally, information was gathered from the Cochrane databases, Google Scholar, bibliographies, and conference proceedings. The systematic review focused on randomized controlled trials that juxtaposed the effects of vaginal progesterone against a placebo or no treatment in women who were asymptomatic but carrying twin pregnancies.

The methodology of the study adhered strictly to the guidelines set out in the Cochrane Handbook for Systematic Reviews of Interventions. The principal metric for evaluation was the occurrence of preterm birth before 34 weeks of gestation. Beyond this, secondary outcomes encompassed various adverse perinatal events. The study employed pooled relative risks accompanied by 95% confidence intervals for statistical analysis. Furthermore, an assessment of each study’s potential bias, heterogeneity evaluation, and examination for publication bias was undertaken. The quality of evidence was also scrutinized, supplemented by subgroup and sensitivity analyses to provide comprehensive insights.

In total, eleven studies, encompassing 3,401 women and 6,802 fetuses/infants, met the criteria for inclusion in the review. For twin pregnancies, there was no notable distinction between the groups treated with vaginal progesterone versus those given a placebo or no treatment concerning the risk of preterm birth before 34 weeks (relative risk, 0.99; 95% CI, 0.84–1.17; high-quality evidence), before 37 weeks (relative risk, 0.99; 95% CI, 0.92–1.06; high-quality evidence), or before 28 weeks (relative risk, 1.00; 95% CI, 0.64–1.55; moderate-quality evidence). Similarly, the risk of spontaneous preterm birth before 34 weeks remained unaffected (relative risk, 0.97; 95% CI, 0.80–1.18; high-quality evidence). No significant impacts on perinatal outcomes were identified. Subgroup evaluations further revealed that vaginal progesterone did not produce varied effects on preterm birth before 34 weeks when considering factors like chorionicity, conception type, previous spontaneous preterm births, dosage, or gestational age at the start of treatment. For unselected twin pregnancies, when compared with placebo or no treatment across eight studies (3,274 women and 6,548 fetuses/infants), no marked variations were observed in the rates of preterm births at various gestational weeks or adverse perinatal outcomes. However, in twin pregnancies where the transvaginal sonographic cervical length was less than 30 mm (in six studies involving 306 women and 612 fetuses/infants), vaginal progesterone showcased significant reductions in the risk of early preterm births, neonatal deaths, and extremely low birth weights. Moreover, in cases where the cervical length was 25 mm or less (in six studies with 95 women and 190 fetuses/infants), vaginal progesterone notably decreased the chances of preterm birth, neonatal complications leading to mortality, and extremely low birth weights.

While vaginal progesterone did not exhibit a preventive effect on preterm births or enhance perinatal outcomes in twin pregnancies as a whole, it displayed potential benefits for pregnancies with a sonographically short cervix, particularly in reducing the risks associated with early gestational ages and adverse neonatal outcomes. Nevertheless, a more extensive body of evidence was essential before advocating the treatment for this specific subgroup of patients.

Source: ajog.org/article/S0002-9378(23)00317-4/fulltext