Vaginal progesterone prophylaxis for preterm birth (the OPPTIMUM study): a multicentre, randomised, double-blind trial

Vaginal progesterone was not associated with reduced risk of preterm birth or composite neonatal adverse outcomes, and had no long-term benefit or harm on outcomes in children at 2 years of age.

The three primary outcomes were obstetric (defined as fetal death or birth before 34 weeks and 0 days gestation, neonatal (defined as a composite of death, brain injury, or bronchopulmonary dysplasia), and childhood (which comprised a standardised cognitive score at 2 years of age).

The researchers conclude that data from this study should prompt a review of the use of progesterone for preterm birth prophylaxis, a search to identify specific women who might benefit, and an increase in efforts to find alternative strategies to prevent preterm birth in women at risk.