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A growing percentage of women of childbearing age are overweight
or obese. Obesity is known to cause menstrual problems, difficulty
getting pregnant, complications during pregnancy, and adverse
pregnancy outcomes.
Maternal obesity has been linked to serious birth defects of the
head and spine (anencephaly and spina bifida). Past studies have
examined links with other birth defects, but the numbers of cases
were too small to provide good estimates.
Data from a national study were analyzed to see how a mother’s
weight affects the risk of certain birth defects.
For this study, researchers used data from the National Birth
Defects Prevention Study, an ongoing, population-based study in nine
states. This CDC-funded case-control study , is the largest of its
kind in the United States and provides sufficient numbers of birth
defect cases to produce more reliable estimates.
Researchers looked at 16 types of birth defects, including oral
clefts, heart defects, neural tube defects, microtia or anotia,
defects of the gastrointestinal system, genitourinary defects, and
limb reductions.
Body mass index (based on a mother’s height and weight) before
pregnancy was used to identify women who were underweight,
overweight, or obese.
Important findings from this study include:
- Maternal obesity was significantly linked with these
defects:
Spina bifida (obesity doubled the risk)
Heart defects
Anorectal atresia
Hypospadias
Limb reductions
Diaphragmatic hernias
Omphalocele
- Underweight was not linked with these birth defects, except
for a modest increased risk of orofacial clefts.
- Maternal obesity slightly increased the risk of cleft palate
and significantly decreased the risk of gastroschisis
- This study supports past findings and offers new evidence
for links between maternal obesity and certain birth defects.
More research is needed to find the reasons for these links.
Waller DK, Shaw GM, Rasmussen SA, Hobbs CA, Canfield MA,
Siega-Riz A-M, et al. Prepregnancy obesity as a risk factor for
structural birth defects. Arch Pediatr Adolesc Med.
2007;161(8):745–50.
Date:
January 14, 2008
Content source: National Center on Birth Defects and Developmental
Disabilities
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