Stanford PRC scientists predict preeclampsia risk with simple blood test

June 15, 2023

Scientists at the March of Dimes Prematurity Research Center (PRC) at Stanford have created a blood test that identifies a woman’s risk of developing preeclampsia, a dangerous and complex condition marked by high blood pressure in pregnancy.

The PRC team identified 18 genes that, when their expression is measured through a simple blood test before a pregnant woman reaches 16 weeks, can predict her risk of developing preeclampsia later in pregnancy.

If brought to a clinical setting in the form of a test, it would be the first preeclampsia test available that could identify women at risk before signs and symptoms are even present.

The study was published in the journal Nature by lead author Dr. Mira Moufarrej, then a Stanford Medicine PhD student in bioengineering and a collaborator at the PRC at Stanford, and colleagues. She said the test performed with a 75% accuracy in identifying women at risk for preeclampsia with or without severe symptoms. The team analyzed 404 samples in 199 pregnant women and were able to identify up to three quarters of women who went on to develop preeclampsia.

If validated in larger studies, the test would be a breakthrough for preeclampsia screening and treatment. Because preeclampsia is complex and not very well understood, it’s either diagnosed in late pregnancy or postpartum, or misdiagnosed completely. This makes it the second leading cause of maternal death globally. However, early screening could lead to preventative treatment, potentially with over-the-counter medications, or through more personalized monitoring and care.

The test, termed a liquid biopsy, works by measuring the cell-free RNA (cfRNA) expression of 18 genes associated with preeclampsia (although the team identified over 500 genes that are affected by the condition). 

In preeclamptic women, those 18 genes are abnormally expressed—either higher or lower than normal expression, much like a sound or signal that’s either brighter or dimmer than expected. These genes, along with hundreds of others that are abnormally expressed in women with the condition, regulate the placenta, the immune system, the brain, and the blood vessels, as well as other organ systems, including the liver, kidneys, muscle, and bone marrow. 

The test is incredibly significant for three reasons. First, it would allow early screening and treatment (there are promising over-the-counter solutions that can improve outcomes if started early in pregnancies at risk for preeclampsia). Second, healthcare providers could treat patients based on which part of the body shows abnormal expression, opening the door for individualized, targeted care. Third, availability of a test that reliably predicts preeclampsia would facilitate drug development and testing, opening the door for exciting novel therapeutic interventions.

Dr. Moufarrej said a test based off this scientific method is already being developed for use clinically, and, if validated, could be available to women in the next several years.