Placental biomarker analysis could be useful to predict pre-eclampsia before 11 weeks of gestation

Some biophysical and biochemical markers (such as PlGF and PAPP-A) in the first trimester of pregnancy, combined with the clinical history and characteristics of a pregnant woman, are able to predict early pre-eclampsia (before 34 weeks of gestation) and preterm (before 37 weeks). Currently, the most widely used prediction models are based on the biomarkers obtained between 11 and 13 weeks, but a new study by Vall d’Hebron Institute of Research (VHIR) shows that the makers have the same capacity of prediction if measured between 8 and 11 weeks. In this way, this analysis could be combined with the one that is usually performed for screening for Down syndrome. This fact would avoid re-puncturing the pregnant woman, as well as giving the result of the two screenings at the same time, when the first trimester ultrasound is performed.

Pre-eclampsia is a syndrome that occurs in 2-8% of pregnant woman and is characterized by hypertension and the presence of protein in the urine. This complication, which appears from 20 weeks of gestation, is the first cause of admission to the intensive care units for pregnant women and, many times, it requires labor induction in order to resolve the symptoms, which can be very serious if they appear early.

This new research, which has been published in the journal Ultrasound in Obstetrics & Gynecology, has been led by the Maternal and Fetal Medicine Unit at the Vall d’Hebron University Hospital. The study followed 2,641 women throughout their pregnancy. Of these, 90 developed pre-eclampsia, 11 of which were early onset and 30 were preterm.

Participating women were classified in to two groups depending on when the predictive biomarkers of pre-eclampsia were analyzed: before or after 11 weeks of gestation. In one of the groups, women were between 8 and 11 weeks, and in the other group they were between 11 and 13 weeks.

The researchers used two algorithms to calculate the risk of pre-eclampsia in these 2,641 pregnant women. One of the algorithms was published by the Fetal Medicine Foundation. The second one was, in part, developed by the same researchers from Vall d’Hebron and was published in January 2020 in American Journal of Obstetrics and Gynecology. These two algorithms obtain a personalized risk based on the maternal history and characteristics, Doppler of the uterine arteries, the mean arterial pressure, PAPP-A and PlGF. Measurement of biomarkers before or after 11 weeks was assessed in this study. The results showed that the predictive capacity of the two algorithms was the same to predict early and preterm pre-eclampsia regardless of when the biomarkers had been measured (before or after 11 weeks).

“These results have important clinical implications, since pre-eclampsia screening could be done at the same time that Down syndrome screening is performed. This would avoid unnecessary punctures and it would allow to give the result of the two screenings at the same time, when the first trimester ultrasound is performed”, highlights Dr. Manel Mendoza, specialist physician in the Obstetrics Service, head of the Placental Insufficiency Unit of the Vall d'Hebron University Hospital and researcher of the Maternal and Fetal Medicine research group at VHIR. 

The findings of this research provide the bases for studies with a larger cohort, with the aim of validating this new screening system with a greater number of cases of early or preterm pre-eclampsia.