The impact of low-dose aspirin on preterm birth: secondary analysis of a randomized controlled trial

Objective:the objective of this study is to determine whether low-dose aspirin (lda) reduced the rate of preterm birth (ptb) in a cohort of women at high risk for preeclampsia.study design:secondary analysis of the maternal-fetal medicine units high-risk aspirin trial. preterm births were categorized by phenotype: indicated, spontaneous or due to preterm premature rupture of membranes (pproms).results:of 1789 randomized women, 30.5% delivered before 37 weeks (18.5% indicated, 5.8% spontaneous and 6.2% following preterm pproms). among women randomized to lda, we observed a trend favoring fewer ptbs due to spontaneous preterm labor and preterm pproms, odds ratio (or: 0.826 (0.620, 1.099)); the incidence of indicated ptbs appeared unchanged, or: 0.999 (0.787, 1.268).conclusion:although not reaching significance, we observed an effect size similar to other studies of both low- and high-risk women. these results support findings from other studies assessing lda as a ptb prevention strategy.