Diet quality in pregnancy influences risk of neural tube and orofacial defects

Women who eat an overall good-quality diet before and during pregnancy have a lower risk of delivering babies with neural tube defects (NTDs) such as anencephaly and spina bifida, and orofacial malformations such as cleft lip and palate, researchers from Stanford University School of Medicine report.

Their study of women from 10 states used data from the National Birth Defects Prevention Study (NBDPS) to analyze 936 cases of NTDs, 2,475 cases of orofacial cleft defects, and 6,147 controls without malformations. Based on the women’s answers to detailed questions about their eating habits immediately before and during pregnancy, researchers assessed overall diet quality using the Mediterranean Diet Score and the Diet Quality Index for Pregnancy (DQI).

After adjusting for confounders, improved diet quality according to either index was associated with decreased risk for neural tube and orofacial defects. The strongest association was between anencephaly and DQI. Significant associations between cleft lip with or without cleft palate and cleft palate and DQI also were observed. The study was published online October 3 in the Archives of Pediatrics and Adolescent Medicine.

“The findings from this study suggest that overall diet quality is more predictive of birth defect risk than intake of single nutrients,” the authors write. The results are notable, they add, “because previous analyses from this same study, the NBDPS, which assessed nutrient intakes in isolation, had not been informative.”

When researchers divided women into 4 comparison groups according to diet quality score, they found that women with the top 25% of scores were 31% to 51% less likely than those with the bottom 25% of scores to have a child with anencephaly, depending on which dietary scoring system was used. Women with the highest scores were about 24% to 34% less likely than those with the lowest scores to give birth to an infant with cleft lip. Higher diet quality also protected against spina bifida and cleft palate, but not as strongly.

While acknowledging that focusing on single nutrients, especially folic acid, has substantially reduced the prevalence of NTDs and perhaps other defects, the researchers note that “if increased dietary quality can indeed have a greater impact than individual nutrients, appropriate public health messages may need to be developed that convey this broader perspective.”

Read other articles in this issue of Special Delivery.