June 8, 2010

Genetics Linked To Premature Births

A large U.K. study found that women who were born prematurely, or had siblings who were, might be at increased risk of having a preterm baby themselves. 

The study involved about 14,000 women who gave birth between the 1970s and 2008.  The findings add to evidence that genes are involved in the risk of preterm delivery.

The researchers discovered that women who were born prematurely had a 35 percent to 49 percent greater chance of preterm delivery.

According to findings published in the journal Obstetrics & Gynecology, the risk to any one woman, however, was not great.

Nine percent of the women born prematurely had a premature baby themselves.  That compared to just over 6 percent of women who had been born full-term.

According to an editorial published with the study, the findings are not going to change how women's pregnancies are managed.

Dr. William H. Barth Jr., of Harvard Medical School and Massachusetts General Hospital in Boston, told Reuters that women who were born preterm do not need to be considered high-risk for premature delivery and monitored with extra prenatal tests.

He says the findings are mainly of interest to researchers trying to uncover the reasons underlying preterm delivery.

Experts believe that preterm birth results from a complex mix of genetic susceptibility and environmental factors and behaviors.  Some of those factors might be smoking and drug use. 

Researchers found, in a recent study that analyzed nearly 1 million births in Sweden, that sisters of women who had delivered preterm had an 80 percent higher risk of early delivery, versus women without that family history.

There was no evidence that the increased risk shared by sisters was explained by non-genetic factors.

Sohinee Bhattacharya and colleagues of the University of Aberdeen used information from a database that has tracked births among Aberdeen-area women since the 1950s for the current study.

The team focused on births to 13,845 women whose own mothers were also included in the database. 

The researchers found that women who had been born prematurely were 49 percent more likely than their full-term counterparts to have a premature infant. 

Researchers are not sure exactly how genes influence preterm-birth risk.  Genes that regulate the conditions of the uterus during pregnancy, for instance, may be involved.  However, that still remains unknown.

According to the team, more studies are needed in order to determine which genes play a role in preterm delivery.


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