Ultrasound tests, now a familiar gold-standard procedure during pregnancy, can show a fetus' development but they're expensive so they're not ideal in poor communities around the world.
"With further study, we might be able to identify specific genes and gene pathways that could reveal some of the underlying causes of preterm birth, and suggest potential targets for interventions to prevent it", he added. Recently released provisional data for 2017 from the National Center for Health Statistics show that the preterm birth rate in the US has reached 9.93 percent, up from 9.86 in 2016, the third consecutive annual increase after steady declines over the previous seven years.
Until now, some tests for predicting premature birth were available but they tended to work only in women at high risk, and were accurate only about 20% of the time, according to the report.
Researchers, led by Professor Steven Kueik of Stanford University, California, who published the journal Science, found a new method that predicts the activity of certain maternal and fetal genes as biomarkers.
Describing the blood test, the research team's principal investigator, David Stevenson, likened it to "eavesdropping on a conversation" between the mother, the foetus and the placenta, without disturbing the pregnancy.
And it is hard to accurately predict delivery dates, she said. They tested the model on the remaining 10 women's blood samples, and found they could predict the baby's age and due date with 45 percent accuracy, or within 14 days of the actual due date.
Preterm births occur in approximately 12 percent of all live births in the US - and it is the cause of about 70 percent of newborn deaths, according to the American College of Obstetrics and Gynecology. The findings indicated that cfRNA corresponding to a set of placental genes might provide an accurate estimate of fetal development and gestational age throughout pregnancy.
She noted that the genes relevant for estimating gestational age were identified using healthy Caucasian Danish women with full-term pregnancies.
Another top researcher was Stephen Quake, professor of bioengineering and of applied physics at Stanford University, who led a team that created a blood test for Down syndrome in 2008 - now used in more than three million pregnant women per year.
Existing medical knowledge has no way of accurately assessing whether any pregnancy will result in an early delivery, but this test was shown to have identified women who would go on to deliver babies up to two months prematurely. From seven cfRNA biomarkers, six out of eight preterm cases were correctly identified. This time, they used blood samples from two previous studies involving 38 women with high-risk pregnancies.
"These tests hold promise for prenatal care in both the developed and developing worlds, although they require validation in larger, blinded clinical trials", the researchers reported.
"It's mostly maternal genes", Moufarrej said, noting that the genes that predict prematurity are different than those that give information about gestational age.