Prevent-PE (pre-eclampsia prevention by timed birth at term): Protocol for a randomised trial

To evaluate whether term pre-eclampsia (PE) is reduced by screening for PE risk at 35 + 0-36 + 6 weeks' gestation and offering risk-based, planned early term birth.

'PREVENT-PE' is a multicentre, randomised trial (ISRCTN41632964).

Singleton pregnancy, presentation for routine fetal ultrasound at 35 + 0-36 + 6 weeks', and can give informed consent.

PE, major fetal abnormality, or participation in a conflicting study. Randomisation (central, 1:1 ratio, minimised for study site, in random permuted blocks) to intervention (screening for term PE risk, and planned early term birth for PE risk ≥ 1 in 50) or control (usual care at term) arms.

Primary: Birth with PE (ISSHP 2021 criteria).

Emergency caesarean and neonatal unit admission ≥ 48 h. Others include within-trial and intermediate-term economic evaluations, and mixed-methods surveys and interviews.

3,201 participants/arm would be required to detect a relative risk (intervention/control) of 0.5, based on 2.0% PE incidence, 90% power, and two-tailed 2.5% significance level; an adaptive design will determine the final sample size (4000-8000) at interim analysis of the first 3,000 participants.

Intention-to-treat. Economic evaluation will measure and value resources and health outcomes for mothers at risk of term PE and newborns (health service perspective). In within-trial cost-effectiveness analysis, the main outcome will be incremental cost per PE case averted, with costs and health outcomes calculated using patient-level data. A decision model will assess cost-utility of the intervention for one year postpartum.

PREVENT-PE will provide data to inform birth choices and maternity services planning.