New Blood Test Could Detect Whether Pregnant Women Will Be Affected by Preeclampsia

A new blood test could detect whether pregnant women will be affected by preeclampsia, which can cause stroke, organ damage and preterm birth, months before its symptoms appear.

Preeclampsia is a blood pressure disorder that occurs in about one out of 20 pregnancies, typically in the third trimester. Pregnancy-related high blood pressure disorders are one of the leading causes of maternal death globally.

The experimental new test, created by Mirvie, a company based in South San Francisco, analyzes chemical messages, a type of RNA, from the mother, baby and placenta, enabling doctors to spot preeclampsia indicators potentially 16 to 18 weeks into a pregnancy. That timeframe is before preeclampsia symptoms, such as swelling, protein in the urine and high blood pressure, would begin to appear.

On Wednesday, the journal Nature published research that showed the test was able to correctly identify 75 percent of women who developed preeclampsia.

"It's often in the first trimester that a lot of the onset of the condition happens biologically," despite symptoms appearing late in pregnancy, Maneesh Jain, Mirvie's CEO, said.

Finding preeclampsia after symptoms show up "leaves you very little time to address the challenge. And it's mostly crisis management," Jain added.

While the blood test is still being made and will not be available for a while, doctors and parent advocates say it could save lives.

Bekah Bischoff of Louisville, Kentucky, who developed preeclampsia during two pregnancies and now helps others who've had the condition, said she was diagnosed late in the third trimester both times. While pregnant with her son Henry in 2012, she found out she had a very severe type called HELLP Syndrome at 36 weeks. He was delivered that day. She nearly died.

"Just think about all the chaos and the heartbreak and all the trauma, really, that went with it that could have been avoided if there had just been a simple test that could have been done," she said.

Diagnosing preeclampsia now involves testing urine for protein, measuring blood pressure and doing other tests if it's suspected. Treatment can involve bed rest, medication, monitoring at the hospital or inducing labor near the end of a pregnancy.

Earlier studies have also suggested circulating RNA could predict preeclampsia. But authors of the Nature study looked at a large and diverse data set, analyzing RNA in 2,539 blood samples from 1,840 women in the U.S., Europe and Africa to get a better sense of how a test could work. After the RNA messages were detected, a computer analyzed them for patterns. Although the test "robustly" predicted preeclampsia in those who got it, the study said, there were also some people it predicted would get the disorder who did not.

Dr. Thomas McElrath of Brigham and Women's Hospital in Boston, the study's senior author, hopes the test could also be used for the early detection of other pregnancy complications, such as gestational diabetes. Scientists said Mirvie's approach reveals the underlying biology of healthy pregnancies. And by understanding what those normal RNA "profiles" look like, researchers say they can find early indications of risks for other problems when these patterns differ in particular ways. More research is needed to look closely at how the test might detect these other conditions, they said, and to further validate the preeclampsia results.

Jain said it's too early to say when the test might be available to the public, but he may have a better idea of timing toward the end of the year. McElrath is a scientific advisor to Mirvie and has an financial interest in the company, as do some other authors of the Nature paper. Some are inventors on patent applications covering detection or treatment of pregnancy complications. The study was paid for by Mirvie.

Dr. S. Ananth Karumanchi with Cedars-Sinai in Los Angeles, who has done extensive research on preeclampsia but was not involved with the Nature study, said detecting the condition early would allow doctors to make simple adjustments such as giving women low-dose aspirin to delay the onset of preeclampsia.

"There's no question there's a clear unmet medical need," Karumanchi said. Looking at the data in the paper, he said, the scientists' method "appears to be better than the current sort of methods that are being used around the world." If validated by other studies, "there would be clearly a need for something like that."

Bischoff, who now works for the Preeclampsia Foundation, agreed. When she was about five months along with her son, she said, she felt drained of energy and was gaining more weight than she thought she should be. But when she asked people on her medical team about these sorts of problems, she recalled, she was told things were normal—like many of the other women she's met who have had preeclampsia.

A blood test, she said, "would take out that barrier of having to fight to be heard."

The Associated Press contributed to this report.