Efficacy of Vaginal Versus Oral Progesterone in Preventing Preterm Birth among Low-Risk Women with a Short Cervix Diagnosed At 20–24 Weeks

Abstract

Introduction: Vaginal progesterone is a proven preventive treatment for women with a short cervix, and a short cervix is an important cause of neonatal morbidity and mortality. There is limited evidence to compare the vaginal and oral routes.

Objective: To evaluate the effectiveness of vaginal and oral progesterone for the prevention of preterm birth in low-risk singleton pregnancies with a sonographically short cervix at 20-24 weeks.

Methods: This is a prospective randomized controlled study carried out at the Department of Obstetrics and Gynaecology, Peshawar Medical College, in the duration from February, 2026 to July, 2026. One hundred and twenty women who had cervical length ≤25 mm were consecutively recruited and randomly assigned to the vaginal (n=60) or oral (n=60) micronized progesterone 200 mg daily until 36 weeks or delivery. Values of p<0.05 were considered significant.

Results: There were no significant differences in baseline variables between groups. The proportion of preterm births (before 37 weeks) was 13.3% versus 23.3% (p=0.17), and before 34 weeks was 5.0% versus 10.0% (p=0.29) in the vaginal and oral groups, respectively. Mean gestational age at delivery was 37.2 ± 1.8 versus 36.5 ± 2.2 weeks (p=0.06). NICU admission occurred in 8.3% versus 15.0% (p=0.26), and adverse effects in 11.7% versus 16.7% (p=0.43).

Conclusion: There was a trend for vaginal progesterone to be superior to oral progesterone, but this was not statistically significant. More large-scale, multi-center studies are required.