Vaginal Progesterone Lowered Preterm Birth Rates in Women with Short Cervices

Preterm birth (PTB) is a major contributor to perinatal morbidity and mortality. In a phase III randomized trial, researchers evaluated vaginal progesterone (90 mg daily) compared with placebo for preventing PTB in 458 asymptomatic women with short cervix (10–20 mm) identified sonographically before 24 weeks' gestation (72 participants had histories of PTB). Participants self-administered 1 gel applicator daily until delivery or 37 weeks. The primary outcome was preterm birth before 33 weeks.

Rates of PTB before 33 weeks were 45% lower in women who received progesterone compared with those who received placebo (8.9% vs. 16.1%; P=0.02), and the authors calculated that 14 women with short cervix would need to be treated to prevent 1 case of PT…