A clinical trial led by the Vall d'Hebron University Hospital has demonstrated the efficacy of the sFIt-1/*PIGF marker in detecting the majority of false positives in the high-risk preeclampsia test. This study, in which eight other Spanish hospitals have participated, has made it possible to stop aspirin treatment in many pregnant women without negative consequences for either the mother or the baby.

The findings published in the journal JAMA show that women classified as high risk for preeclampsia and who have a normal sFIt-1/*PIGF value (38 or lower) between the 24th and 28th week are in fact false positives. This indicator can be measured with a blood test. These patients will be able to stop treatment and return to the protocol for low-risk pregnancies, which will help to reduce anxiety in expectant mothers and reduce the possible complications of aspirin.

"This study confirms what we have suspected for some years, that aspirin to prevent preeclampsia is only necessary during the first half of pregnancy in most cases. For these women, continuing treatment until delivery does not seem to be beneficial and could lead to unnecessary complications. This research allows us to reduce the use of unnecessary medications in pregnancy, moving towards a more physiological and less medicalized management of pregnancies", explains Dr. Manel Mendoza, head of the Placental Insufficiency Unit within the High Obstetric Risk Unit of Vall d'Hebron and researcher of the Maternal and Fetal Medicine research group of the Vall d'Hebron Research Institute (VHIR) and principal investigator of the study.

The study followed 936 women who had a positive preeclampsia screening test during the first trimester and an sFIt-1/PlGF value of 38 or lower in a blood test performed during the second semester (between the 24th and 28th week). Between one test and the other, all had followed a daily treatment with aspirin 150 mg, according to the protocol for monitoring pregnancy in Catalonia. After the analysis, half of the women in the study continued with the usual dosage and the other half, stopped the treatment. The result was that there was no difference between the incidence of preeclampsia in one group and the other, which means that this angiographic indicator is effective in detecting the false positives of the first-trimester screening.

A standard test that saves lives, but has many false positives

The test for preeclampsia in the first trimester (between the 11th and 13th week of gestation) is a standard test in the pregnancy monitoring protocol in Catalonia. The test is a combined analysis of different measurements, ultrasound and laboratory tests. With it, 10-15% of all pregnant women are considered at high risk of preeclampsia and are recommended to take aspirin every day until the end of pregnancy.

Preeclampsia is a serious multisystem disorder that complicates between 2 and 4% of pregnancies. In most cases, it does not present symptoms until the third trimester, when it can trigger arterial hypertension and proteinuria (the presence of protein in the urine). Untreated preeclampsia can lead to premature delivery, restricted fetal growth, premature placental abruption, seizures, multiple organ failure and life-threatening permanent damage to the pregnant woman and her unborn child. The problem is that although symptoms become evident in the third trimester, for preventive aspirin treatment to be effective it is essential to start before week 16. Aspirin treatment can reduce the risk of preeclampsia by up to 80%.

Until the discovery of this indicator, despite knowing that preeclampsia is a rare disease and, therefore, that the majority of patients at high risk of preeclampsia were false positives, due to the severity of the pathology, that the use of aspirin is relatively safe and that prevention should be initiated before 16 weeks, it was considered better to offer treatment to all patients at high risk than to run the risk of not medicating pregnancies that could develop the disorder.

More than 90% of patients will be able to stop treatment in the second trimester.

The new protocol incorporating the angiogenic indicator, proposed by the Maternal-Fetal Medicine research group at VHIR, offers a solution. With a simple blood test between the 24th and 28th week, false positives among women identified in the first trimester as high risk of preeclampsia can be found. In more than 90% of women, treatment can be stopped without any negative consequences for them or their babies. This test does not give reliable results until the second trimester, and between tests, pregnant women are advised to undergo treatment, as the benefits outweigh the risks.

The research team believes that, based on this trial, strategies should be designed to be able to stop aspirin treatment when it is not necessary. They recall that aspirin is an antiplatelet drug that increases the risk of bleeding, and in this study, it was shown that stopping treatment also reduced the risk of minor bleeding, especially of the gums, nose, and genitals.

Apart from the risk reduction, such a measure will prevent overmedication and promote peace of mind among pregnant women, reducing their anxiety and risk of complications. Unfortunately, angiogenic indicators are not yet available in all hospitals and for this reason, it will be necessary to wait until the new protocol can be incorporated into clinical practice