A new study published in the journal Archives of Pediatrics and Adolescent Medicine reveals that women who are obese before they become pregnant are more likely to have babies with birth defects than are mothers of normal weight before pregnancy. Scientists and healthcare professionals have long suspected the link but this is the first comprehensive large-scale study to confirm those suspicions.
Over a five-year period, University of Texas researchers interviewed more than fifteen-thousand new mothers from eight states, five-thousand of whom had healthy babies and ten-thousand of whom had babies with birth defects. Each women was asked her height and weight at the time of conception as well as various other questions. From that information, researchers found that more than two-thousand of the participants were obese before they became pregnant.
The study found abnormalities of the heart, spine, feet, fingers, arms, legs, and abdomen. The birth defect most strongly linked to obesity is spina bifida. Obese women had more than twice the risk of giving birth to a baby with spina bifida. Other birth defects that were strongly linked to obesity prior to pregnancy include omphalocele, heart defects, shortened arms and legs, and various gastrointestinal deformities. The two most common gastrointestinal deformities were malformations of the genitals and diaphragmatic hernia.
Despite the findings, researchers stress that the risk of having a baby with a birth defect is low, regardless of weight before conception. The likelihood of a woman who is obese at the time of conception giving birth to a baby with a birth defect is only slightly higher than that of a woman who is a healthy weight at the time of conception. The researchers found that obese women had about a four percent chance of having a baby with birth defects while a women of healthy weight have about a three percent chance.
Researchers are uncertain how to explain the findings. Some believe that the defects are a direct result of obesity at the time of conception. Others believe that various factors may have caused the defects, such as diet. For example, it is known that incidents of spina bifida can be greatly reduced with better nutrition and the addition of folic acid to the diet during pregnancy. It is possible that the women in the study did not get sufficient nutritional intake. It is also possible that participants in the study had undiagnosed diabetes, which is linked to certain birth defects. The study did not examine weight during pregnancy. Therefore, it is not known if that had any effect on the findings.
At this time, researchers do not want women to be overly concerned. The findings are not particularly alarming since the increase in risk is only slight and the exact cause for the increase is not currently known. Overweight and obese women are being advised to eat a healthy, balanced diet before and during pregnancy. They are also being urged to not attempt to lose weight during pregnancy through aggressive methods such as diet pills or fasting, both of which can increase the risk for birth defects.