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Healthier dietary choices by pregnant women are associated with reduced risks of birth defects, including orofacial clefts and neural tube defects, according to a new study (Archives of Pediatrics & Adolescent Medicine, Online First, Oct. 3, 2011).
Folic acid supplementation and food fortification have been effective in preventing neural tube defects, but folic acid does not prevent all birth defects. Nutrition research on birth defects has tended to focus on one nutrient at a time, but nutrition is much more complex.
Suzan Carmichael, PhD, of Stanford University, in Stanford, CA, and colleagues used data from the National Birth Defects Prevention Study to examine whether better maternal diet quality was associated with reduced risk for selected birth defects. The data were collected in 10 states from pregnant women with estimated due dates from October 1997 through December 2005.
Information was collected via telephone interviews with 72 percent of case and 67 percent of control mothers. Included in the analysis were 936 cases involving neural tube defects, 2,475 involving orofacial clefts, and 6, 147 controls without birth defects. Mothers reported their food intake using a questionnaire.
The researchers developed two diet quality indices that focused on overall diet quality based on the Mediterranean Diet and the U.S. Department of Agriculture Food Guide Pyramid.
The researchers found that increasing diet quality based on either index was associated with reduced risks for the birth defects studied. Most mothers of controls were non-Hispanic white women who had more than a high school education. Nineteen percent smoked, 38 percent drank alcohol, and 78 percent took supplements with folic acid during early pregnancy. Sixteen percent were obese.
"Women who were Hispanic had substantially higher values for the Diet Quality Index [DQI] and the Mediterranean Diet Score [MDS], whereas values were lower among women with less education and women who smoked, did not take supplements, or were obese," the researchers found. "Higher maternal diet quality in the year before pregnancy was associated with lower risk for neural tube defects and orofacial clefts. This finding persisted even after adjusting for multiple potential confounders such as maternal intake of vitamin/mineral supplements."
The results suggest that "dietary approaches could lead to further reduction in risks of major birth defects and complement existing efforts to fortify foods and encourage periconceptional multivitamin use," they concluded.
The project was partially supported by grants from the National Institutes of Health and the Centers for Disease Control and Prevention.
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