Reduced risks of neural tube defects and orofacial clefts with higher diet quality.

OBJECTIVE

To examine whether better maternal diet quality was associated with reduced risk for selected birth defects.

DESIGN

A multicenter, population-based case-control study, the National Birth Defects Prevention Study.

SETTING

Ten participating centers in the United States.

PARTICIPANTS

Eligible subjects' estimated due dates were from October 1997 through December 2005. Telephone interviews were conducted with 72% of case and 67% of control mothers. Analyses included 936 cases with neural tube defects (NTDs), 2475 with orofacial clefts, and 6147 nonmalformed controls.

MAIN EXPOSURES: Food-frequency data were used to calculate the Mediterranean Diet Score (MDS) and Diet Quality Index (DQI), modeled after existing indices.

MAIN OUTCOME MEASURE: Adjusted odds ratios (ORs).

RESULTS

After covariate adjustment, increasing diet quality based on either index was associated with reduced risks for the birth defects studied. The strongest association was between anencephaly and DQI; the OR for highest vs lowest quartile was 0.49 (95% CI, 0.31-0.75). The ORs for cleft lip with or without cleft palate and cleft palate and DQI were also notable (0.66 [95% CI, 0.54-0.81] and 0.74 [95%CI, 0.56-0.96], respectively).

CONCLUSIONS

Healthier maternal dietary patterns, as measured by diet quality scores, were associated with reduced risks of NTDs and clefts. These 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.