Researchers at Stanford University may have found an easier, more affordable alternative to ultrasounds, which typically help pregnant women determine when their child will be born and whether their pregnancies will end in premature birth.
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In a new study published in the journal Science last week, the researchers reported that a simple blood test may provide the necessary information as reliably as the ultrasound, a current gold standard that isn't always affordable in areas with low resources and doesn't predict spontaneous preterm birth, the leading cause of infant mortality in the United States.
For the paper, the researchers recruited 31 pregnant women from Denmark who underwent weekly blood tests throughout their pregnancies.
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These tests, according to the study, measured the “activity of maternal, placental and fetal genes” by examining blood levels of cell-free RNA, molecules responsible for translating DNA and carrying the genetic instructions to the body’s “protein-making factories.”
As a woman’s pregnancy progressed, the scientists noticed changing levels of the cell-free RNA in certain genes, which offered signs about gestational age and prematurity risk.
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"We found that a handful of genes are very highly predictive of which women are at risk for preterm delivery," co-author Mads Melbye said in a news release. "I've spent a lot of time over the years working to understand preterm delivery. This is the first real, significant scientific progress on this problem in a long time."
By building a statistical model using blood samples from 21 of the 31 Danish women, the researchers predicted the gestational age for the remaining 10 women. The model estimates were accurate about 45 percent of the time, comparable to the 48 percent accuracy of first-trimester ultrasound estimates.
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Furthermore, to understand how to predict preterm birth, the largest contributor to death before age 5 among the world’s children, the scientists studied blood samples of 38 American women at risk for premature delivery.
Women experiencing early contractions or those who have had previously given birth to a preterm baby are considered at risk. Of the 38 women, 13 delivered prematurely.
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Blood samples during their second or third trimesters showed that levels of cell-free RNA from seven genes from the mother and placenta helped predict which pregnancies would end early, according to the research.
"This gives a super-high resolution view of pregnancy and human development that no one's ever seen before," author Thuy Ngo of the Oregon Health and Science University said in a news release. "It tells us a lot about human development in normal pregnancy."
But the researchers believe more research needs to be completed with larger cohorts of pregnant women before blood tests can be made available for clinicians.
