New York, Feb 3 (IANS): Variants in the genetic material of the foetus - not the mother - may be the trigger for some premature births, a research has found.

"These findings really open a whole different arena for us to look into as we think about preterm birth," said Joseph Biggio, professor at University of Alabama at Birmingham, US.

We have always thought about preterm birth as a maternal issue, but these data change the paradigm. It may be the fetus who has the underlying predisposition, not the mother," Biggio said.

For the study, Biggio analysed the number of copies of certain segments of DNA in the blood or saliva from hundreds of babies and their mothers.

No link was established between the number of copies of the mother's genes and the risk of preterm birth; however, there was a two- to 11-fold increase in preterm births before 34 weeks of gestation among infants in whom any of four particular genes was duplicated or any of seven other genes was deleted.

While the differences in the number of copies of the genes or gene regions may not directly cause a preterm birth, they may make a baby more susceptible to infection or reacting to other harmful environmental factors that trigger early labour and delivery, Biggio said.

"These findings may help explain what triggers early labor in some women even when they've done everything right during pregnancy and there's no obvious cause for an early birth," Edward McCabe, chief medical officer at March of Dimes Foundation, said.

The March of Dimes is scheduled to present its award for Best Research in Prematurity to Biggio for this work during the annual Society for Maternal-Fetal Medicine meeting, which began Feb 2 in San Diego, California.