OC13.01: Placental growth factor at 24–28 weeks for aspirin discontinuation in pregnancies at high risk for pre‐eclampsia: post‐hoc analysis of StopPRE trial

This study aims to evaluate the safety of discontinuing aspirin treatment at 24 to 28 weeks in women at high-risk after first trimester combined screening for pre-eclampsia (PE) and normal placental growth factor (PlGF) levels at 24 to 28 weeks of gestation. This is a post hoc analysis of the StopPRE trial, conducted at nine Spanish maternity hospitals from September 2019 to September 2021. In the StopPRE trial, all high-risk single pregnancies identified during first trimester screening for PE were treated with 150mg daily aspirin. Out of 1,604 eligible women with soluble fms-like tyrosine kinase-1 to placental growth factor ratio (sFlt-1/PlGF) ≤38 at 24-28 weeks, 968 were randomly assigned in a 1:1 ratio to either continue aspirin until 36 weeks (control group) or discontinue it (intervention group). In this secondary analysis, only women with a PlGF ≥100 pg/mL at 24-28 weeks were included. As in the StopPRE trial, the non-inferiority margin was set at a 1.9% difference in preterm PE incidence between groups. Among 13,983 screened pregnant women, 1,984 (14.2%) were deemed high-risk for preterm PE, of which 397 (20.0%) were ineligible, 636 declined participation, and 32 were excluded. Ultimately, 919 women with PlGF >100 pg/mL were randomised and included in this analysis. Preterm PE occurred in 0.9% of the intervention group (4 out of 465) and 1.5% of the control group (7 out of 454), indicating non-inferiority of aspirin discontinuation. There were no significant differences between groups in adverse pregnancy outcomes before 37 weeks, or at <34 weeks, or ≥37 weeks. Minor antepartum hemorrhage incidence was significantly lower in the intervention group (absolute difference, -5.96; 95% CI, - 10.10 to -1.82). Discontinuing aspirin treatment at 24-28 weeks in women with PlGF ≥100 pg/mL was non-inferior to continuing until 36 weeks in preventing preterm PE.