Maternal Obesity Heightens Risk of Birth Defects

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The link between overweight and obesity and other birth defects has been less clear.

According to the U.S. Agency for Healthcare Research and Quality, as many as one in 33 babies born in the United States has a birth defect.

For the new study, the largest of its kind, Waller and her colleagues interviewed 10,249 women in eight states whose babies had been born with birth defects between 1997 and 2002. Information on the women came from the National Birth Defects Prevention Study.

These women were then compared to 4,065 women who had given birth to babies without birth defects during the same time period.

Sixteen birth defects were studied. Of those, mothers of babies with the following seven birth defects were more likely to have been obese than mothers of infants without birth defects:

• Spina bifida, or the incomplete development of the brain, spinal cord and/or meninges (the protective covering around the brain and spinal cord). This is the most common neural tube defect in the United States and affects up to 2,000 of the more than 4 million babies born annually, according to the National Institutes of Health.
• Heart defects.
• Anorectal atresia, or malformation of the anal opening.
• Hypospadias, or an abnormally placed urethral opening in males -- on the underside instead of the end of the penis.
• Limb reduction defects, such as small or missing toes, fingers, arms or legs.
• Diaphragmatic hernia, an opening in the diaphragm that allows abdominal organs to move into the chest cavity. This may also cause lungs to be underdeveloped.
• Omphalocele, when the intestines or other abdominal organs protrude through the navel.

The study authors noted that the overall risk of having a child with a birth defect related to obesity is low. And mothers of babies born with gastroschisis (when organs protrude through a defect in the abdominal wall other than the navel) were less likely to be obese than mothers of babies without birth defects.

The findings are published in the August issue of Archives of Pediatrics & Adolescent Medicine.