Obesity Increases Birth Defect Risk
Heart, Spine, and Limb Defects Seen More
Aug. 6, 2007 -- Babies born to mothers who are obese prior to and during
pregnancy are at increased risk for a range of major birth defects, new
Pre-pregnancy obesity has previously been linked to an increase in birth
defects involving the brain and spinal cord. This association was seen in the
new study, and researchers also reported an increase in heart, limb, and
gastrointestinal birth defects among babies born to obese moms.
Obese women were at increased risk for delivering babies with seven of 16
major birth defects evaluated by the researchers.
But researcher D. Kim Waller, PhD, of the University of Texas School of
Public Health, tells WebMD that the chance of delivering a child with a major
birth defect is still low for obese moms.
According to Waller, based on the study’s findings, major birth defects
could be expected in four out of 100 babies born to obese mothers. The average
birth defect risk is closer to three in 100 births among babies born to
normal-weight mothers, he notes.
"Obese women should not be overly alarmed by these findings, but it is
important to understand the risk," she says. "While the absolute risk
that an obese woman will have an infant with a birth defect is low, the
contribution to the public health, given high rates of obesity in the U.S., is
Twofold Rise in Spina Bifida
Interviews were conducted with 10,249 women in eight states who gave birth
to babies with birth defects between 1997 and 2002 and with 4,065 women who
delivered babies without birth defects during the same period.
The birth defect found to be most strongly linked to obesity in the study
was the neural tube defect spina bifida.
Compared with babies born to normal-weight women, babies born to obese women
in the study were twice as likely to have the neural tube defect even though
obese moms were just as likely to take folic acid supplements prior to
Taking folic acid before pregnancy dramatically reduces the risk of spina
bifida and related neural tube birth defects.
A slightly lower increase in risk was identified for omphaleocele, a
condition in which the intestines or another abdominal organ protrudes through
Obesity-related risk increases in the range of 20% to 50% were also seen for
heart defects, limb abnormalities, malformations in the anal opening or urethra
in boys, and a condition known as diaphragmatic hernia, which can interfere
with lung development.
The study is published in the August issue of the Archives of Pediatric
and Adolescent Medicine.
Diabetes and Birth Defects
Having uncontrolled or poorly controlled diabetes prior to conception or
early in pregnancy has been linked to an increased risk for major birth defects
in both animal and human studies.