New Blood Test Accurately Predicts Preeclampsia

A new blood test has 80 percent accuracy in predicting preeclampsia in premature births, according to a study published in the journal Nature Medicine.

The Test Uses Cell-Free DNA Released by the Placenta During Pregnancy

The disease, which causes over 70,000 maternal deaths and 500,000 fetal deaths worldwide each year, has long been difficult to predict. This makes proactive treatment difficult, according to one of the study’s lead authors. “The placenta is something we can’t biopsy during pregnancy, but we think is critical to the development of preeclampsia,” said Dr. Swati Shree, a UW Medicine obstetrician-gynecologist and co-author on the paper. “Doctors do look at clinical risk factors, which can work quite well, but there are still many people that get missed.”

Preeclampsia is a pregnancy complication characterized by high blood pressure (hypertension) or organ dysfunction. It typically occurs during the third trimester. The exact cause of the condition is not known, but doctors suspect it is related to an abnormal interaction between the placenta and the mother’s blood vessels. Traditionally, doctors have tried to determine a pregnant woman’s risk based on her medical history. Risk factors for preeclampsia include first pregnancy, a history of preeclampsia, a history of high blood pressure or chronic kidney disease, or both. However, sometimes preeclampsia develops even without any of these preexisting conditions.

Researchers have known for at least two decades that the placenta releases DNA into the maternal blood. Labs are able to extract cell-free DNA, sequence it and use the sample to screen for fetal anomalies such as Down syndrome. Previously, these tests were sent to outside labs for processing, but in 2017, UW Medicine became one of the first health systems to begin running these tests in-house. Teams at UW Medicine and the Fred Hutch Cancer Center collaborated on developing the idea of using cell-free DNA sequence data to screen for preeclampsia.

Test Aims to Become a Tool for Early Detection of Preeclampsia

Over the past two years, the researchers, led by Shree and co-corresponding author Gavin Ha, a bioinformatician at Fred Hutch, have used this liquid biopsy data from the first trimester of pregnancy from over 1,000 pregnant women to develop and subsequently validate their test. “The innovation of this tool highlights its importance. Liquid biopsy testing was developed in pregnancy health research and is now an emerging field in oncology research,” said Ha. ”There are similarities in the genes we are studying in both research areas, making this study a collaboration that connects the two fields.”

The samples were taken between 2017 and 2023. The researchers found that their approach, which uses signals stored in circulating cell-free DNA sequence data, had an 80% sensitivity in predicting whether or not a pregnant person would experience premature preeclampsia. Shree said that the next steps would be to improve the training model with more samples and eventually conduct a study involving thousands of patients. The researchers hope that such a test could become an early preeclampsia detection tool that can be seamlessly integrated into routine screening in early pregnancy.