Preterm preeclampsia is an important cause of maternal and perinatal death and complications. It is uncertain whether the intake of low-dose aspirin during pregnancy reduces the risk of preterm preeclampsia. In this multicenter, double-blind, placebo-controlled trial, we randomly assigned 1776 women with singleton pregnancies who were at high risk for preterm preeclampsia to receive aspirin, at a dose of 150 mg per day, or placebo from 11 to 14 weeks of gestation until 36 weeks of gestation. The primary outcome was delivery with preeclampsia before 37 weeks of gestation. The analysis was performed according to the intention-to-treat principle. A total of 152 women withdrew consent during the trial, and 4 were lost to follow up, which left 798 participants in the aspirin group and 822 in the placebo group. Preterm preeclampsia occurred in 13 participants (1.6%) in the aspirin group, as compared with 35 (4.3%) in the placebo group (odds ratio in the aspirin group, 0.38; 95% confidence interval, 0.20 to 0.74; P=0.004). Results were materially unchanged in a sensitivity analysis that took into account participants who had withdrawn or were lost to follow-up. Adherence was good, with a reported intake of 85% or more of the required number of tablets in 79.9% of the participants. There were no significant between-group differences in the incidence of neonatal adverse outcomes or other adverse events. Treatment with low-dose aspirin in women at high risk for preterm preeclampsia resulted in a lower incidence of this diagnosis than placebo. (Funded by the European Union Seventh Framework Program and the Fetal Medicine Foundation; EudraCT number, 2013-003778-29; Current Controlled Trials number, ISRCTN13633058.)

Objective: To examine the performance of screening for preterm and term pre‐eclampsia (PE) in the study population participating in the ASPRE (Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence‐Based Preeclampsia Prevention) trial.Methods: This was a prospective first‐trimester multicenter study on screening for preterm PE in 26 941 singleton pregnancies by means of an algorithm that combines maternal factors, mean arterial pressure, uterine artery pulsatility index and maternal serum pregnancy‐associated plasma protein‐A and placental growth factor at 11–13 weeks' gestation. Eligible women with an estimated risk for preterm PE of > 1 in 100 were invited to participate in a double‐blind trial of aspirin (150 mg per day) vs placebo from 11–14 until 36 weeks' gestation, which showed that, in the aspirin group, the incidence of preterm PE was reduced by 62%. In the screened population, the detection rates (DRs) and false‐positive rates (FPRs) for delivery with PE < 37 and ≥ 37 weeks were estimated after adjustment for the effect of aspirin in those receiving this treatment. We excluded 1144 (4.2%) pregnancies because of loss to follow‐up or study withdrawal (n = 716), miscarriage (n = 243) or termination (n = 185).Results: The study population of 25 797 pregnancies included 180 (0.7%) cases of preterm PE, 450 (1.7%) of term PE and 25 167 (97.6%) without PE. In combined first‐trimester screening for preterm PE with a risk cut‐off of 1 in 100, the DR was 76.7% (138/180) for preterm PE and 43.1% (194/450) for term PE, at screen‐positive rate of 10.5% (2707/25 797) and FPR of 9.2% (2375/25 797).Conclusion: The performance of screening in the ASPRE study was comparable with that of a study of approximately 60 000 singleton pregnancies used for development of the algorithm; in that study, combined screening detected 76.6% of cases of preterm PE and 38.3% of term PE at a FPR of 10%. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.