Single blood sample predicts preeclampsia in pregnant women faster than ever before

BOSTON — A new blood test can identify preeclampsia, a potentially life-threatening condition in pregnant women faster than ever before. State-of-the-art RNA sequencing from a single blood sample can predict the ailment.

Preeclampsia affects about one in 25 pregnant women in the U.S., including celebrity moms like Kim Kardashian and Mariah Carey. The condition reduces the flow of blood through the placenta, and can lead to stillbirth or even the death of the mother. While in many women the symptoms are mild, in some cases the condition becomes so severe the baby needs to be delivered prematurely.

The study, led by a group of scientists from around the world, was sponsored by Mirvie, a San Francisco company developing RNA tests for pregnancy complications. By studying 1,840 pregnancies, the researchers created a method to assess the health and normal progress of pregnancy. The method was tested on preeclampsia and produced a seven-fold improvement in correctly predicting the disease compared to current methods.

At the moment, imaging techniques such as ultrasound, and other minimally invasive procedures are powerful tools for assessing pregnancy health and progression. But a detailed, ongoing assessment of the well-being of the baby and placenta is difficult. Doctors also still lack tools to preemptively identify those at risk of pregnancy complications such as preeclampsia.

The researchers explain that analyzing which maternal, fetal, and placental genes are “activated” at sequential points in pregnancy could provide more detail about the stage of gestation. It may also reveal whether certain complications, either in the mother, placenta or fetus, might occur.

By analyzing maternal, fetal, and placental RNA that circulates in a mother’s blood during pregnancy, the team identified patterns of gene expression associated with a healthy pregnancy. They also found patterns that correctly predicted a risk of preeclampsia in 75 percent of cases and a risk of preterm birth at nearly the same rate.

“Looking at the progression of genes expressed in the mother and baby during pregnancy offers an entirely new way of characterizing their health that hasn’t been available up until now,” says senior author Thomas McElrath, of Brigham and Women’s Hospital, in a statement. “Early detection of disease using this approach will provide us with the distinct possibility of therapeutically addressing some of these conditions.”

The genetic material analyzed by the researchers can be extracted through a single blood test from the mother and sheds light on the molecular functioning of the placenta and fetal organs as well as maternal tissues such as the cervix and uterus. Overall, the technique developed by the team to estimate pregnancy progression performed equally as well as a second trimester ultrasound, and better than a third trimester ultrasound

The researchers found that their screening model, developed by identifying seven genes consistently involved in preeclampsia, produced a seven-fold improvement in correctly predicting the disease compared to current methods. A positive test also correctly identified 73 percent of moms who ultimately had a delivery complicated by preeclampsia over three months before clinical symptoms appeared.

The research team says that window could allow doctors to prepare clinical interventions for women identified to be at risk. They add that clinical factors such as age, race and weight did not improve the performance of their screening model.

“For those of us working in women’s health care, it’s exciting to see advanced technological innovation coming into play in this field because innovation has not always been as frequent,” says McElrath. “While much research is understandably dedicated to diseases that occur at the end of life, this discovery opens up a new set of tools that can be brought to bear on problems that occur at the very beginning of life.”

The findings are published in the journal Nature.

South West News Service writer Stephen Beech contributed to this report.