Prophylactic oral nifedipine to reduce preterm delivery: a randomized controlled trial in women at high risk

Objective: To establish the efficacy of prophylactic nifedipine vs. placebo in reducing spontaneous preterm delivery in asymptomatic women at high risk for preterm delivery.

Design: Prospective multicentric randomized double-blind study.

Setting: Tertiary care centre, University Hospitals of Brescia and Torino, Italy.

Population: Eighty-seven singleton pregnancies without uterine contractions and ultrasonographic cervical length of ≤25 mm at 24-32 weeks, at risk for preterm delivery, with longitudinal follow up in our Preterm Prevention Clinic.

Methods: Selection was done on the basis of ultrasonographic cervical length; 43 women were randomized to receive placebo and 44 to receive nifedipine.

Main outcome measures: Primary end point: spontaneous preterm delivery <37 weeks in nifedipine vs. placebo.

Secondary outcomes: delivery <32 weeks, maternal side effects, neonatal complications, admissions to the Neonatal Intensive Care Unit and randomization/delivery time in nifedipine vs. placebo.

Results: There was no trend towards a lower risk of spontaneous preterm delivery, neither at <37 weeks of nifedipine vs. placebo (11.4% vs. 19.0%; p = 0.320), or <32 weeks (2.3% vs. 2.4%; p = 0.973). Nifedipine reduced spontaneous preterm delivery <37 weeks (p = 0.015) in the multiparous women by stratified analysis for parity. SECONDARY OUTCOMES between the groups did not differ except for a higher percentage of maternal side-effects in the nifedipine group (31.8%) vs. placebo (11.9%) (p < 0.05). Subgroup analysis showed a borderline (p = 0.047) lower percentage of spontaneous preterm delivery in women with a ultrasonographic cervical length of <20 mm in the nifedipine group.

Conclusions: Prophylactic nifedipine in asymptomatic women at high risk for preterm delivery had a positive effect on the rate of spontaneous preterm delivery <37 weeks in multiparous women.