ow dose aspirin in the Prevention of Recurrent Spontaneous Preterm Labour – the APRIL study

From 31 May 2016 to 13 June 2019, 406 women were randomised of which 387 were included in the analysis: 194 women were allocated to aspirin and 193 to placebo. Preterm birth <37 weeks occurred in 41 (21.2%) women in the aspirin group and 49 (25.4%) in the placebo group (RRR 0.83, 95% CI 0.58 to 1.20, p=0.323). In women who were =80% compliant with medication, preterm birth occurred in 19.2% versus 24.8% (RRR 0.77, 95% CI 0.48 to 1.25, p=0.291). There was significant effect modification by gestational age of the previous preterm birth (interaction term p=0.042), with women with a previous preterm birth <30 weeks of gestation (RRR 0.59, 95% CI 0.23 to 1.02, p=0.059) having more benefit from aspirin than those with a previous preterm birth =30 weeks. The rate of poor neonatal outcome was 4.6% versus 2.6% (RRR 1.79, 95% CI 0.61 to 5.25, p=0.288).