TUESDAY, April 5, 2011 (HealthDay News) -- Babies born to mothers who were obese in early pregnancy have a much greater risk of dying before, during, or up to one year after birth, a new British study says.
Researchers examined nearly 41,000 pregnancies involving deliveries of single babies at five maternity units in northern England from 2003 to 2005.
The risk of a baby dying in the womb (fetal death) or up to one year after birth (infant death) was twice as high among women who were obese (BMI of 30 or more) in early pregnancy than among those with normal weight (BMI of 18.5 to 24.5).
There were nearly eight more fetal and infant deaths per 1,000 births among obese women than among women with normal weight. The total (absolute) risk of fetal or infant death was 16 in every 1,000 births (1.6 percent) among obese women and nearly 9 per 1,000 births (0.9 percent) among normal weight women.
The lowest risk was among women with a BMI of 23. BMI, or body mass index, is a ratio of weight to height. A BMI of 25 to 29.9 is considered overweight and a BMI of 30 or greater is considered obese.
The study was published April 5 in the journal Human Reproduction.
"There are likely to be a number of reasons why obesity is associated with fetal and infant death and we don't yet know the full story," study co-author Judith Rankin, a professor of maternal and perinatal epidemiology at Newcastle University, said in a journal news release. "For example, there is an increased risk of high blood pressure or diabetes developing during pregnancy. Understanding the risks associated with obesity is helpful for health-care professionals caring for pregnant women, so that additional monitoring can be provided as necessary."
Most women in the United Kingdom and other developed nations "will deliver a healthy live baby, regardless of their weight at the start of pregnancy," Dr. Ruth Bell, clinical senior lecturer at Newcastle University, said in the news release.
"What's key is that women should be helped to achieve a healthy weight before they become pregnant or after the baby is born. Our research shows that this will give the baby the best possible start in life. Women should not try to lose weight during pregnancy, but should ensure they eat a balanced healthy diet," she said.
The U.S. National Women's Health Information Center offers healthy pregnancy advice.