Obese pregnant women are at great risk of having babies with a wide range of birth defects, according to an analysis published in the February 11 issue of the Journal of the American Medical Association.

 

The findings are based on a review of 39 studies which pointed out that obese women had twice the risk of having babies born with spina bifida or with holes in the wall separating their heart chambers.

 

“Our review confirms that maternal obesity raises the risk of a range of congenital anomalies. This has health implications, particularly given the continued rise in the prevalence of obesity in many countries,” said lead researcher Katherine Stothard and colleagues from Britain’s Newcastle University.

 

According to background information of the study, more than 30 percent of women older than 15 years were obese in 2004 in the United States, which may lead to an increased rate of birth defects. Birth defects account for 1 in 5 infant deaths in the United States. Worldwide, around 400 million people are classified as obese, including 20 million under the age of five, and the number keeps growing, according to the World Health Organization.

 

But what being obese means? According to the US National Institutes of Health, overweight people have a body mass index of 25 to 29.9, while obese people have a BMI of 30 or greater. Body mass index is a measure of body fat based on height and weight.

 

According to the review, obese women had twice the risk of having babies with spina bifida; 30 percent higher risk of having babies with cardiovascular defects; 20 percent higher risk of babies with cleft lip and cleft palate, either singly or together; 60 percent higher risk of babies with hydrocephaly (an abnormal buildup of fluid in the brain); and 30 percent higher risk of babies with limb reduction abnormalities.

 

Why does obesity increase the risk of birth defects? The authors of the review said that obesity is a strong risk factor for type 2 diabetes, a condition that is known to lead to birth defects, especially of the central nervous system and the heart.

 

Furthermore, maternal obesity was linked to nutritional deficiencies, especially reduced folate levels. Women of childbearing age are urged to take 400 micrograms of folic acid per day to protect their baby against spina bifida, but the quantity may not be enough if they’re obese, the researchers said.

 

Although the findings are worrisome, study senior author Judith Rankin, a reader in maternal and perinatal epidemiology at Newcastle University pointed out that “birth defects occur in between 2 to 4 percent of all pregnancies, so the risk, even in obese women, remains low. If a woman who is obese is thinking of having a baby, the most important thing is to speak to their doctor and to think about their weight and diet so that they eat healthily and sensibly.”