A blood test may one day be able to predict whether someone who is pregnant will develop a serious blood pressure disorder months before symptoms show up.
Preeclampsia happens in around one of 20 pregnancies, usually in the third trimester, and can cause organ damage, stroke and preterm birth. Pregnancy-related high blood pressure disorders are among the leading causes of maternal death worldwide.
Although the blood test is still being developed and won't be available for a while, doctors and parent advocates say it could someday save lives.
The experimental new test involves detecting and analysing chemical messages — a form of RNA — from the mom, baby and placenta. It would allow doctors to spot indications of preeclampsia as early 16 to 18 weeks into the pregnancy, before the appearance of symptoms such as high blood pressure, swelling and protein in the urine. Research published Wednesday in the journal Nature found that the test, being developed by the South San Francisco-based company Mirvie, can correctly identify 75 per cent of women who go on to develop preeclampsia.
“It's often in the first trimester that a lot of the onset of the condition happens biologically,” although symptoms show up late in pregnancy, said Maneesh Jain, Mirvie's CEO. Detecting preeclampsia after symptoms arise “leaves you very little time to address the challenge. And it's mostly crisis management.”
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 labour near the end of a pregnancy.
Earlier studies have also suggested circulating RNA could predict preeclampsia. But authors of this study looked at a large and diverse data set, analysing 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 analysed 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 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.