In two separate cohorts of women, all at elevated risk of delivering preterm, the research team identified a set of cell-free RNA (cfRNA) transcripts that accurately classified women who delivered preterm up to two months in advance of labor.
The blood test can predict with 80% accuracy whether a woman will give birth prematurely. The technique can also be used to estimate a fetus's gestational age - or the mother's due date - as reliably as and less expensively than ultrasound.
"It's mostly maternal genes", says Stanford University medical researcher Mira Moufarrej. The genetic activity reveals physiological changes in the tissues and organs of both the mother and the baby - and clues of distress that can precede premature delivery. By applying their model, the researchers correctly guessed whether the women would deliver preterm more than 75 percent of the time, according to the paper published in the journal Science. The other method, the ultrasound, can also be problematic because it gives less reliable information as a pregnancy progresses and doesn't predict spontaneous preterm birth (not to mention the equipment and trained technicians needed makes this option really expensive).
In the second test, researchers studied blood samples from 38 pregnant women who were already at risk of preterm labor because of early contractions or a previous preterm delivery. At present, the test has a precision of about 45% in predicting a baby's birth time, compared with 48% of ultrasound in the first trimester of pregnancy.
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The scientists found that levels of cell-free RNA from seven genes from the mother and the placenta could predict which pregnancies would end early.
"RNA corresponding to placental genes may provide an accurate estimate of fetal development and gestational age throughout pregnancy", the report found.
Researchers said the new test, which still needs more testing and improvement, may be a simpler, cheaper and perhaps more reliable method than ultrasounds in the future. "We think it's mom sending a signal that she's ready to pull the ripcord".
Quake, Tibshirani, Shaw and Stevenson are members of Stanford Bio-X; Tibshirani, Shaw and Stevenson are members of the Stanford Child Health Research Institute; Quake and Tibshirani are members of the Stanford Cancer Institute; Stevenson is an affiliate of the Stanford Woods Institute for the Environment; and Quake is a member of the Stanford Cardiovascular Institute, Stanford ChHEM-H and the Stanford Neurosciences Institute. According to the news outlet, delegates from nation's largest physicians group are expected to vote on a resolution to encourage birth control manufacturers to submit applications to the FDA to switch the status of their pills from prescription to over the counter.
Stanford's departments of Bioengineering, Applied Physics and Pediatrics also supported the work.