Premature birth rates are rising in the UK
A drug used to treat cancer can stop contractions and may prevent premature labour, researchers say.
The Newcastle University team tested the drug Trichostatin A on tissue taken from 36 women undergoing a caesarean.
The researchers said the therapy worked by increasing the levels of a protein that controls muscle relaxation.
One expert said with rates of premature births rising - there are 50,000 a year in the UK - a new treatment was badly needed.
Preterm labour and birth continue to be the single biggest cause of death in infants in the developed world and around 1,500 babies die in the UK every year.
A number of drugs are used to try to stop early labour, but most have serious side effects.
Trichostatin A (TSA) is known to promote the death of cancer cells.
The researchers got permission to take samples of the muscles of women undergoing caesarean sections at the Royal Victoria Infirmary in Newcastle, the Cellular and Molecular Medicine journal reported.
They exposed the muscle to TSA and measured the effects on both spontaneous contractions and those induced by the labour drug, oxytocin.
They found an average 46% reduction in contractions for the spontaneously contracting tissue and an average 54% reduction in the oxytocin induced contractions.
It has been previously shown that a protein kinase A (PKA) is involved in controlling the relaxation of the uterus during pregnancy.
The researchers showed that TSA increased the levels of a protein sub-unit of PKA.
Professor Nick Europe-Finner, who led the research, said: "We will not give this drug to a patient because it can damage as many as 10% of the genes in a cell.
"But it does show us that other more specific agents that act on the same enzymes but only one at a time are worth investigating."
Dr Yolande Harley, deputy director of research at Action Medical Research which funded the study, said: "This project has uncovered some of the molecular pathways that regulate uterine contractions and so could be linked to premature birth.
"It could have a role in preventing premature birth - finding a new treatment for early labour would be a major step forward."
Professor Jane Norman, a spokeswoman for the Royal College of Obstetrics and Gynaecology (RCOG), said: "At the moment, it's not possible to treat preterm labour effectively. We only have drugs that delay it by 24 hours or so - not enough to deliver the baby safely.
"One of the interesting things about this research is that they are using a new kind of drug - the drugs we are currently using have been around for a long time.
"And they are targeting pathways we have not known about before.
"When you consider that preterm birth rates are rising in all four countries of the UK a new more effective drug is badly needed."