Preventing Preterm Birth in Nulliparous Women: Aspirin for All?

Preterm birth underlies a considerable burden of infant death and disability, particularly in low- and middle-income countries (LMICs). Interventions to screen and treat at-risk women have proven costly but have yet to substantially reduce the prevalence of this adverse outcome. In earlier trials of strategies to prevent hypertensive disorders of pregnancy, women who received aspirin had lower rates of preterm birth; accordingly, investigators conducted a trial to assess the benefits of daily low-dose aspirin on risk for preterm birth among 12,000 unselected nulliparous women in six LMICs. Participants were randomized to 81-mg aspirin or placebo daily, starting between 6 and 14 weeks' gestation and ending at 36 weeks and 7 days or delivery.…