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- A new blood test may predict preeclampsia, a deadly pregnancy complication, early.
- The test, developed by UW Medicine and Fred Hutch researchers, showed 80% accuracy.
- Researchers aim to expand testing and hope it becomes a routine screening tool.
SALT LAKE CITY — A new blood test has potential to identify a hard-to-predict but sometimes deadly pregnancy complication weeks before it would normally be found, leading to early treatment and possibly prevention.
Preeclampsia kills 70,000 women and 500,000 babies worldwide every year, according to background material for a study just published in the journal Nature Medicine.
The pregnancy complication is marked by high blood pressure and can lead to liver or kidney damage and is not usually detected until after the 20th week of pregnancy and sometimes quite a bit later, according to Medline Plus. It's most common in the third trimester. A rarer form occurs soon after the baby is delivered.
While its cause is not known, experts believe the condition starts with an "abnormal interaction between the placenta and the mother's blood vessels," the researchers note.
"The placenta is not something we can biopsy during pregnancy, but we believe it is integral to developing preeclampsia," Dr. Swati Shree, a UW Medicine OB-GYN and co-corresponding author of the paper, said in the news release. "Doctors do look at clinical risk factors, which can work reasonably well, but it still misses a fair amount of people."
Absent a test, doctors have looked for risk factors, including it being the woman's first pregnancy or whether she has a history of preeclampsia, high blood pressure or chronic kidney disease or some combination of those. But not everyone has those risk factors.
The idea for the blood test
Research stretching back more than two decades has shown that during pregnancy, the placenta sheds DNA into the mother's blood. Extracting and sequencing cell-free DNA has formed the basis of some screening tests used to detect genetic abnormalities in developing babies, such as Trisomy 21 (Down syndrome).
It also sparked the idea used by the University of Washington Medicine and Fred Hutch Cancer Center researchers to develop a blood test for preeclampsia.
Researchers used cell-free DNA sequence data from 1,000 women taken during the first trimester of pregnancy between 2017 and 2023. The sequence data was described in the release as "a liquid biopsy" that let them screen for preeclampsia and validate the test, which proved to be 80% accurate in showing whether a pregnancy would lead to preeclampsia.
"The innovation in this tool reinforces how important it is. Liquid biopsy tests were pioneered in pregnancy health research and is now an emerging research area in oncology," said one of the study's corresponding authors, Gavin Ha, a computational biologist at Fred Hutch. "There are similarities in the genes we're looking at in both areas of research, which makes this study a collaboration which bridges both fields."
Researchers hope to expand validating the test to include thousands of patients and said they'd like to see the blood test prove itself and become a routine early screening tool.
"Although using liquid biopsies for human diseases is largely used in the cancer area, given the frequency at which cell-free DNA screening is performed, prenatal biology truly has incredible opportunities for the discovery and application of innovative tools," Shree said.
More about preeclampsia
Medline has a more extensive list of risk factors for preeclampsia and reported it may be more common in those who have autoimmune disorders or blood vessel problems. It notes that diet and genetics may be involved. Other risk factors include past history of a growth-impaired baby, carrying more than one baby at a time, obesity, being older than 35, a gap of more than 10 years between pregnancies, diabetes, a history of thyroid disease and an IVF pregnancy.
Symptoms can be subtle; women often do not feel sick with the condition. But Medline Plus notes that swelling of the hands and face or around the eyes may be a sign, as is sudden weight gain (over the course of a day or two) or gaining more than 2 pounds a week. Swollen feet and ankles are not predictive as they are a normal part of pregnancy.
More severe symptoms of preeclampsia include:
- Persistent headache or one that worsens.
- Breathing difficulty.
- Belly pain on the right side, below the ribs or in the right shoulder.
- Less frequent urination.
- Nausea and vomiting — "a worrisome sign," Medline Plus reports.
- Vision changes or light sensitivity.
- Feeling lightheaded.
Preeclampsia requires careful monitoring, and after 37 weeks, the provider is likely to deliver the baby to avoid the condition worsening. Sometimes, a C-section is needed. But bed rest is no longer routinely recommended, per the article.
