Cedars-Sinai research led the Food and Drug Administration (FDA) in July 2023 to approve a blood test to predict preeclampsia in preterm pregnant women.

In a blinded, prospective study of pregnant women initially hospitalized for preterm hypertension, Cedars-Sinai investigators found that a specific imbalance of two placental proteins could predict which women were at risk of developing a severe form of preeclampsia. The study, which involved 1,014 patients from 18 hospitals across the nation, was published in the journal NEJM Evidence.

“We discovered that a blood test measuring the ratio between soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF) in the bloodstream could identify which of the women would develop preterm preeclampsia with severe features. This test was significantly better than all the standard-of-care markers for that condition,” said maternal-fetal medicine specialist and study co-senior author Sarah Kilpatrick, MD, PhD, who is chair of the Department of Obstetrics and Gynecology and holds the Helping Hand of Los Angeles Chair in Obstetrics and Gynecology at Cedars-Sinai.

Produced by Thermo Fisher Scientific, the new blood test—intended for women in the 23rd to 35th weeks of pregnancy—can identify with 96% accuracy which women will develop preeclampsia within the following two weeks.

In the Cedars-Sinai study, an sFlt-1-to-PlGF ratio of 40 or greater predicted the development of serious preeclampsia, adverse outcomes and early delivery within two weeks. If the critical ratio between the two proteins was below 40, the risk that the patient would progress to preeclampsia with severe features within two weeks was less than 5%.

The novel B·R·A·H·M·S PlGF plus KRYPTOR and B·R·A·H·M·S sFlt-1 KRYPTOR tests are automated immunofluorescent assays for the quantitative determination of the concentration of PlGF and of sFlt-1 in human serum and plasma (EDTA). In approving the tests, the FDA directed physicians to use them in conjunction with one another, “along with other laboratory tests and clinical assessments to aid in the risk assessment of pregnant women hospitalized for hypertensive diseases of pregnancy for progression to preeclampsia with severe features within two weeks of presentation.”

Rates of preeclampsia have been steadily on the rise, largely due to increases in obesity and hypertension in the nation. Black, American Indian and Alaska Native women have significantly higher rates of the diseases, and a higher risk of death, than white women.

“Our intention is that this blood test could eventually lead to better health outcomes for mothers and their babies. Having an accurate test helps us ensure the mother is in the right hospital for management of her care and that of her preterm baby,” said Kilpatrick.

This test is now available in the U.S., but physicians will have to check if it is available in their hospital. It is approved only for preterm patients with hypertension. The study’s investigators hope the test may prove to be an important first step on the path to developing potential drug therapies for women at risk of preeclampsia.

“Ultimately, we would like patients with preeclampsia to be able to safely remain pregnant longer, to reduce the risk of very preterm birth,” Kilpatrick said.