Blood test scans for genetic signature to help predict premature labour

Scientists have developed a prototype blood test to predict whether pregnant women who give signs of early labour will in fact give birth prematurely.

The test, which checks the mother's blood for a distinct gene expression profile, looks to fill an area of unmet medical need. Current tests to distinguish false from true labour are imprecise. They have a high rate of false positives and are accurate only 30 to 40 percent of the time.

Principal researcher Professor Stephen Lye, of Mount Sinai Hospital in Toronto, Canada, said his team wanted to develop the test 'so that women in true labour can receive the appropriate medical care while women in false labour will receive supportive care and be discharged'.

Threatened preterm labour (TPTL) is common, and roughly one in ten pregnant women will experience it. However, only five percent of these will give birth within ten days of having contractions.

For the rest, the labour will prove to be false; the contractions will fade and they will eventually give birth at or near full term. As a result, a lot of TPTL women are admitted unnecessarily to hospital. These women, Professor Lye told The Canadian Press, 'will be given drugs to try to stop the labour, which have some side-effects, and these steroids, which may or may not be good for the baby'.

In the study that led to the development of the test, researchers took blood samples from 156 women admitted with TPTL. Forty-eight of these women gave birth within 48 hours of admission. The team analysed patterns of gene expression in their blood samples and compared them with those from women whose labour had been false.

They discovered that activity in nine genes, coupled with clinical blood data, could predict true or false labour in 70 percent of cases — not ideal, but an improvement on the most accurate currently available test.

Professor Lye told The Canadian Press that said that he was talking to companies about developing the test commercially. He added, however, that the test would have to be thoroughly trialled before it would be made widely available. 'It's important not to have the public think there's a test tomorrow', he said. 'It's promising, it's exciting and it's evolving [but] this has to be validated'.