Publication:

Comparative efficacy of oral versus vaginal micronized progesterone in the prolongation of preterm labour: a prospective comparative study

Background Preterm labour is a leading cause of neonatal morbidity and mortality worldwide. Progesterone supplementation is an established strategy for preterm birth prevention; however, the optimal route of administration- oral or vaginal- remains debated, particularly regarding gestation prolongation. Objective was to compare the efficacy of oral versus vaginal micronized progesterone (200 mg daily) in prolonging gestation in women presenting with preterm labour.

Methods A prospective comparative study was conducted at Maharani Laxmi Bai Medical College, Jhansi, from May 2025 to April 2026. One hundred pregnant women with preterm labour (24-36+6 weeks) were randomised to oral micronized progesterone 200 mg daily (group A, n=50) or vaginal micronized progesterone 200 mg daily (group B, n=50). Primary outcomes were mean prolongation of gestation (days) and mean gestational age at delivery (weeks).

Results Both groups were comparable at baseline. The vaginal progesterone group demonstrated significantly greater mean gestation prolongation (20.14±4.58 versus 11.38±2.82 days; p=0.0001) and higher mean gestational age at delivery (35.81±1.09 versus 33.88±1.84 weeks; p=0.001). Deliveries at 33-36+6 weeks were more frequent in the vaginal group (94% versus 74%; p=0.02). Very preterm deliveries (24-29 weeks) occurred only in the oral group (2%).

Conclusions Vaginal micronized progesterone is significantly more effective than oral progesterone in prolonging gestation in preterm labour, attributable to enhanced uterine bioavailability via the first uterine pass effect. It should be the preferred route in clinical management of preterm labour.