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Prepregnancy Obesity Linked to Birth Defects


 

Maternal obesity before pregnancy significantly increased the risk for offspring with anorectal atresia, hypospadias, limb reduction defects, diaphragmatic hernia, and omphalocele in a large study.

D. Kim Waller, Ph.D., of the University of Texas School of Public Health, Houston, and her associates used data from the National Birth Defects Prevention Study to assess whether maternal weight affected risk for several categories of structural birth defects. This is the first study to report a link between maternal obesity and these five types of defects using sufficient sample sizes of 150 or more cases.

More than half of American women aged 20–39 years are estimated to be overweight (with a body mass index [kg/m

The investigators analyzed data on 10,249 babies born with structural birth defects in eight states between 1997 and 2002, as well as 4,065 control subjects representative of the general population.

Maternal obesity was found to raise the risk for spina bifida and heart defects, confirming the findings of previous studies. It also significantly increased the risk for anorectal atresia, hypospadias, limb reduction defects, diaphragmatic hernia, and omphalocele, with odds ratios ranging from 1.3 to 1.6. Maternal obesity also carried a borderline increase in risk for cleft palate, the researchers said (Arch. Pediatr. Adolesc. Med. 2007;161:745-50).

Maternal overweight significantly increased the risk for heart defects, hypospadias, and omphalocele, and slightly raised the risk for craniosynostosis.

Unlike previous studies, this analysis failed to demonstrate an association between maternal obesity and anencephaly, hydrocephaly, or cleft lip. However, this finding may have been the result of chance, because the number of cases of these three birth defects was relatively low.

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