Prevent-PE (Pre-Eclampsia Prevention by Timed Birth at Term): Protocol for a Randomised Trial

Objectives: To evaluate whether term pre-eclampsia (PE) can be reduced by screening for PE risk at 35 ⁺⁰ –36 ⁺⁶ weeks’ gestation and offering women risk-based, planned term birth. Study design : ‘PREVENT-PE’ is a pragmatic, multicentre, randomised trial. Inclusion: singleton pregnancy, presentation for routine fetal ultrasound at 35 ⁺⁰ -36 ⁺⁶ weeks’ gestation, and able to give informed consent. Exclusion: PE, major fetal abnormality, or participation in another study that may influence trial outcomes. Randomisation (central, 1:1 ratio, minimised for study site, in random permuted blocks) to the intervention (screening for term PE risk, and planned early term birth for PE risk ≥1 in 50) or control arm (usual care at term). Outcomes : Primary: Birth with PE, by the International Society for the Study of Hypertension in Pregnancy (2021). Key secondaries: emergency caesarean rate and neonatal unit admission for ≥48 hours, to primary hospital discharge or 28 days postnatal, whichever is earlier. Other: health economics and social science evaluation via mixed-methods survey and interviews. Analysis : A sample size of 6,204 (3,201/arm) would be required to detect a relative risk (intervention/control) of 0.5, based on 2.0% PE baseline incidence, 90% power, and two-tailed 2.5% significance level. However, an adaptive design will determine the final sample size (4,000-8,000) at interim analysis of the first 3,000 participants (computer simulations implemented in R statistical software). Analyses will be intention-to-treat. Ethics approval (London–Dulwich, National Research Ethics Service Committee, 22/LO/0794) and trial registration (ISRCTN 41632964) are in place. Conclusions : PREVENT-PE will provide data to inform birth choices and planning of maternity services.