Premature babies often have to struggle to survive
Premature labour, the major cause of death and disability among babies, may be prevented by blocking a key protein, a study suggests.
Infection is now a recognised trigger of preterm birth, but some women seem to go into labour early even when the infection is trivial.
Researchers at Imperial College London say they can isolate the protein which seems to spark this reaction.
Premature births have been estimated to cost the UK nearly £1bn every year.
Very premature babies often die within the first few days of life, while many others can spend months in intensive care.
Those who do survive are at risk of developing serious disabilities such as cerebral palsy, blindness and deafness, as well as learning difficulties.
The protein - Toll-like receptor 4, or TLR4 - is found on the surface of the cells.
When it recognises bacteria, it sparks inflammation, and it is this which appears to induce premature birth.
However while bacteria are found in the womb of most pregnant women, the vast majority do not respond in this way.
And while the reaction is thought to have an evolutionary basis - potentially saving the life of the mother when a serious bug is present - it occurs in women who have no such infection.
The team at Imperial College London said they had found a way of effectively shutting down this reaction.
Professor Philip Bennett, lead researcher from the Clinical Institute of Obstetrics and Gynaecology at Imperial College London, said: "We are excited about the findings of this research as we have now discovered how to block a key pathway which leads to premature birth.
"Although more research needs to be done, we believe this is a step forward in the development of treatments to prevent premature birth."
Dr Yolande Harley, deputy director of research at Action Medical Research, which funded the study, said: "This research will lead to improvements in understanding the mechanisms that cause premature birth and its impact could be significant if treatments that block this pathway are shown to prevent premature labour."
Bliss Chief Executive Andy Cole said: "We welcome this interesting piece of research and anything that helps us better understand the causes of premature birth.
"This is a step in the right direction. However, there is still much more to do to prevent babies being born too soon."