Objective: To develop models for prediction of preeclampsia (PE) based on maternal characteristics, biophysical and biochemical markers at 11–13 weeks’ gestation in which the gestation at the time of delivery for PE is treated as a continuous variable. Methods: This was a screening study of singleton pregnancies at 11–13 weeks including 1,426 (2.4%) that subsequently developed PE and 57,458 that were unaffected by PE. We developed a survival time model for the time of delivery for PE in which Bayes’ theorem was used to combine the prior information from maternal characteristics with uterine artery pulsatility index (PI), mean arterial pressure (MAP), serum pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PLGF) multiple of the median (MoM) values. Results: In pregnancies with PE, there was a linear correlation between MoM values of uterine artery PI, MAP, PAPP-A and PLGF with gestational age at delivery and therefore the deviation from normal was greater for early than late PE for all four biomarkers. Screening by maternal characteristics, biophysical and biochemical markers detected 96% of cases of PE requiring delivery before 34 weeks and 54% of all cases of PE at a fixed false-positive rate of 10%. Conclusions: A new model has been developed for effective first-trimester screening for PE.

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.