Planned birth at term reduces the incidence of preeclampsia in women at high risk of the condition, without increasing emergency Cesarean or neonatal unit admission, according to new trial results.
The PREVENT-PE trial, led by researchers from King’s College London and King’s College Hospital NHS Foundation Trust, is the first to find that a strategy of screening for preeclampsia risk at 36 weeks of pregnancy, and then offering planned early term delivery according to the mother’s risk, can reduce the incidence of subsequent preeclampsia by 30%, compared with usual care.
The trial also found that the intervention did not increase the rates of birth by emergency Cesarean or neonatal care needs, and there was no evidence of other harms to mother or baby.
The findings were published in The Lancet.
Preeclampsia background and risk factors
Preeclampsia is high blood pressure that develops during pregnancy, most commonly at term gestational age. Preeclampsia affects 2–8% of pregnancies worldwide and can be life-threatening—there are around 46,000 maternal deaths due to preeclampsia each year and around 500,000 fetal or newborn deaths.
Preeclampsia usually develops after 20 weeks of pregnancy, or soon after the baby is born. While aspirin can be taken to significantly reduce the risk of developing preeclampsia before 37 weeks of pregnancy, there are no treatments available to reduce risk at term (37–42 weeks).
Trial design and risk assessment process
Building on findings from an earlier data analysis, the PREVENT-PE trial recruited over 8,000 women from King’s College Hospital and Medway NHS Foundation Trusts. Women were randomly allocated into one of two groups: the intervention group (risk assessment for preeclampsia, followed by planned early term delivery according to risk) and the control group (usual care at term).
Preeclampsia risk was assessed using a model developed by the FMF, which combines maternal demographics and history, with blood pressure, and specific markers in the blood.
Those at high risk of developing preeclampsia at term were offered planned birth at 37, 38, 39 or 40 weeks of pregnancy. Women considered to be at low risk received usual care, according to their hospital protocols and UK standards of care.
Expert commentary and future directions
Professor Kypros Nicolaides, founder and chairman of the Fetal Medicine Foundation, and senior author of the paper, said, “A 30% reduction in term preeclampsia, from 5.6% to 3.9%, is very important. It represents an even greater reduction in the number of preeclampsia cases than we can achieve for preterm preeclampsia with aspirin.”
Dr. Argyro Syngelaki, Reader in Maternal-Fetal Medicine at King’s College London and co-lead author of the paper, said, “This trial took place in busy NHS maternity units serving a highly diverse population, and often socially deprived communities where the burden of preeclampsia is greatest.
“The high level of participation and adherence shows that a personalized, risk-based approach is acceptable, practical, and aligns with what women want from their care. Achieving a 30% reduction in term preeclampsia, without increasing emergency Cesarean birth or neonatal admissions, represents a meaningful and reassuring improvement for women, babies, and maternity services.”
Professor Laura A. Magee, Professor of Women’s Health at King’s College London and co-author of the paper, said, “We will soon report on the health economic implications of the trial, as well as the experiences of women and staff who participated, to provide policy-makers with the information that they need to implement the trial intervention within the NHS.”