Researchers have discovered that premature birth appears to run in families and say it could be genetic.
The study by researchers at the University of Aberdeen found that women born prematurely or with brothers or sisters born early were 50-60 more likely to have a premature baby in their first pregnancy, and 50% more likely with subsequent pregnancies.
Andy Cole, chief executive of Bliss, the special care baby charity, told the BBC: "We welcome any research that helps us better understand the causes of preterm birth and identify those at high risk.
"While this study's findings are interesting, further research is still needed in this area.
"The development of a reliable test for premature birth is vital in ensuring our most vulnerable babies have the best possible outcomes."
Does premature birth run in your family?