A simple saliva test could help spot which expectant women are likely to go into premature labour, experts believe.Early identification would enable these mothers to be given steroids which help in the development of the baby’s lungs, preventing disability and death.

UK researchers found women going into labour very early, before 34 weeks gestation, had abnormally low progesterone levels in their saliva.

Their study appears in the British Journal of Obstetrics and Gynaecology.

Each year in the UK more than 50,000 babies are born prematurely, before 37 weeks gestation, and the condition is still not well understood.

Experts suspect that the hormone progesterone plays some part and studies are underway to test whether giving women more of this hormone during pregnancy cuts the risk of a preterm birth.

The latest work by researchers at University College London and King’s College London, suggests monitoring progesterone levels in saliva could provide a cheap and convenient early marker for the condition.

When they studied 92 women deemed to be at increased risk of having a preterm birth, they found the women who delivered spontaneously before 34 weeks had much lower salivary levels of progesterone than those giving birth at term, after 37 weeks.

This measurable difference in progesterone was apparent at all gestational ages from 24 weeks onwards.

Simple check

It is not clear how the hormone influences the timing of labour, but experts do know progesterone has anti-inflammatory properties, suggesting low levels of the hormone in the maternal body might contribute to bacterial infection - a recognised cause of preterm birth.

Lead author Professor Lucilla Poston, from the Maternal and Foetal Research Unit at King’s College London, said they were now planning a much larger study to validate these preliminary findings.

BBC