New blood test could predict risk of pre-term birth

A blood test could help identify women at risk of premature delivery.
A blood test could help identify women at risk of premature delivery. Photo: Shutterstock

A simple non-invasive  blood test could identify women at risk of pre-term delivery as well as accurately - and inexpensively - predict a baby's due date, say a team of international researchers. "Ultrasound, the current gold standard, is not always affordable in low-resource settings and does not predict spontaneous pre-term birth, a leading cause of infant death," the team, lead by Stanford Medicine, write in a paper published this week in Science.

Study co-author Dr Mads Melbye said that she and her colleagues, using blood samples from mothers-to-be, discovered that a "handful of genes" were highly predictive of which women are at risk of giving birth prior to 37 weeks. "I've spent a lot of time over the years working to understand pre-term delivery," Dr Melbye noted. "This is the first real, significant scientific progress on this problem in a long time."

As part of the first of two pilot studies, a group of 31 Danish women, all of whom delivered at full-term, provided blood each week throughout their pregnancies. The researchers analysed samples from the expectant women and identified nine cell-free RNAs ("tiny bits of the messenger molecule that carry the body's genetic instructions to its protein-making factories"), produced by the placenta, that predicted gestational age.

Using the technique, estimates of a baby's due date were accurate about 45 percent of the time, comparable to 48 per cent accuracy for first-trimester ultrasounds, "but at substantially lower cost".

The team then turned their attention to whether the test could predict spontaneous pre-term delivery. They looked at blood samples from 38 American women who were deemed at risk of delivering early. Three delivered prematurely, while the remaining 25 delivered at full-term. The researchers found that their test was able to predict with 75-80 per cent accuracy, which pregnancies would end early, via seven genes from the mother and the placenta. 

"It's mostly maternal genes," said co-author Mira Moufarrej. "We think it's mum sending a signal that she's ready to pull the ripcord."

While the findings could have important implications in the future, before we start seeing the tests in the clinic as part of routine antenatal care, a larger, more diverse sample of women need to be studied in a clinical trial. Nevertheless, the researchers are positive and believe the results could eventually improve the nature of pre-natal care in both the developed and developing worlds.

"The tests are both affordable and accessible," the authors say. "In addition, it opens the door to new types of tests like predicting pre-term delivery which before wasn't an option. Together all of this means that women all over the world will have better pre-natal care. Hopefully that means healthier pregnancies and healthier babies."

According to the Miracle Babies Foundation, each year approximately 27,000 babies are born premature and around 1,000 will die. Babies who survive may face lifelong challenges including cerebral palsy, health conditions, behavioural disorders, and difficulties at school.

Founder Melinda Cruz, whose three sons all arrived prematurely, says that welcoming a baby early is one of the scariest moments a parent can go through, especially when it happens without warning. Along with fear and worry, Ms Cruz says mothers often express guilt and a feeling of "could I have done anything different?" This is precisely why she believes the idea of a blood test, which could help identify those at risk, would be so significant.

"When there are so many unknowns, a test like this could change a mother's approach to her pregnancy and the medical care she is given long before any signs of a premature labour become apparent,"Ms Cruz says. "This could then change the outcome for their baby.

"It certainly offers families hope."