The Comprehensive Clinical Trials Unit at UCL



20 December 2018

Screening programme for pre-eclampsia

Pre-eclampsia is a medical condition characterised by high blood pressure and the presence of protein in the urine of a pregnant woman. It develops in 2-3% of all pregnancies. The effects of pre-eclampsia can be serious both for the mother and the baby, especially when the disease is severe requiring delivery before 37 weeks' gestation and there is associated slow growth of the baby.

The National Institute for Health and Clinical Excellence (NICE) recommends that the way to determine whether a woman is at high-risk of developing pre-eclampsia should depend on maternal risk factors: However this method of screening only identifies about 40% of the women that develop pre-eclampsia requiring delivery before 37 weeks and 35% of all cases of pre-eclampsia.

A new method of screening that combines maternal risk factors with the results from various tests to calculate the individual risk for developing preeclampsia has been developed. Extensive research in the last decade has led to the identification of four potentially useful tests: measurements of blood pressure, blood flow in the maternal blood vessels that supply the womb and the levels of two placental hormones in the mother's blood (pregnancy associated plasma protein-A [PAPP-A] and placental growth factor [PlGF]). These tests can be carried out at the time of the routine ultrasound examination at 11-13 weeks’ gestation. Prior to this study there was some evidence that the new test is superior to that of the NICE method. The aim of the study was to evaluate the effectiveness of the new method against that currently recommended by NICE using the Bayes’ theorem-based method.

In this prospective multicentre cohort study, carried out in seven National Health Service maternity hospitals in England, between April 2016 and December 2016, women with singleton pregnancies undergoing routine prenatal 11-13 weeks' scan were invited to participate.

The 17,051 women who consented and were eligible and to the screening had maternal characteristics and medical history and measurements of mean arterial pressure (MAP), uterine artery pulsatility index (UtA‐PI), serum placental growth factor (PlGF) and serum pregnancy‐associated plasma protein‐A (PAPP‐A) recorded. Risks calculated using the Bayes' theorem‐based methods were not made available to the participants or their clinicians. Participants received routine standard of care.

At the end of the study, following collection of pregnancy outcome data (obtainable for 16,747), the performance of screening for pre-eclampsia by the Bayes' theorem‐based method was compared with that of the NICE method.

Study status: Completed. 

Results: The analysis has been performed and the results published in Ultrasound in Obstetrics & Gynecology on 14 March 2018.


Funder: NIHR - EME

Sponsor: This study was sponsored by King's College London but authority for study management was delegated to UCL CCTU.