News

New research suggests preterm birth may run in families

May 26, 2010

By Patricia Nicholson

In a recent study, women who were born prematurely, or who had a sibling who was born preterm, were more likely to have a premature infant themselves than women with no family history of preterm birth.

According to background information in the study, preterm birth is the leading cause of perinatal illness and death, and accounts for more than half of serious post-birth complications and disabilities in infants. Delivery between 24 and 37 weeks gestation is considered premature or preterm birth.

Previous research has shown that some women may be predisposed to giving birth prematurely. A woman who has had a premature birth in the past has an increased risk in later pregnancies, and a woman who has had two premature births has an even higher risk of having another. Until now, research exploring preterm births within families has been inconclusive.

A new study of family links in premature births appears in the June 2010 issue of Obstetrics & Gynecology. U.K. researchers analyzed information on mothers and daughters who had both given birth to at least one child. Using information from the Aberdeen Maternity Neonatal Databank, the researchers identified and compared pregnancies in two groups of women:

The family history group comprised the grown daughters of women who had a premature birth. These were women who were either born preterm themselves, or whose mothers had given birth to another infant prematurely.

A control group was made up of daughters of women who had never had a premature birth.

The researchers then looked at the number of premature births in each group. In total, they analyzed more than 22,000 pregnancies, including 1,846 in women with a family history of premature birth.

The results showed that women in the family history group were 35 per cent more likely to give birth prematurely than women in the control group.

The risk was higher for specific family history subgroups: for women who were themselves born prematurely, the risk of delivering a preterm infant was 49 per cent higher than in women in control group. The risk was highest in these women for their first child, with 60 per cent greater odds of a preterm baby compared to women in the control group.

Other factors that were associated with preterm birth in the study included young age (under 20), smoking more than 10 cigarettes per day, and having a low BMI (under 20). Having a previous preterm infant more than doubled the risk of giving birth prematurely.

These results suggest that the risk of preterm birth is higher in women who were themselves born prematurely, or who had premature siblings. If this is confirmed in further studies, it may help doctors identify women at greater risk for preterm delivery.

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