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Birth defects less likely if mums have good diet

Higher quality prepregnancy diet associated with lower birth defects risk

Louise Prime

Wednesday, 05 October 2011

A generally higher quality diet before women become pregnant is associated with a lower risk of birth defects including neural tube defects and orofacial clefts, shows research published online first in this week’s Archives of Pediatrics & Adolescent Medicine.

The importance of folic acid in reducing women’s risk of having a baby with neural tube defects is well known. Researchers in California have now investigated the association between women’s consumption of a generally ‘healthy’ diet before pregnancy, and the likelihood of their baby having one of several birth defects.

They used data from the National Birth Defects Prevention Study, in which new mothers in 10 US states had been interviewed in detail about their food intake in the year leading up to conception. The mothers’ reported diet was rated on two scales that measure overall diet quality, the Mediterranean Diet Score (MDS) and the US Government’s food quality index (DQI), which is based on a food guide pyramid.

The study authors analysed dietary information for 936 cases of neural tube defects, 2475 orofacial clefts and 6147 controls without such defects.

Hispanic women generally scored much more highly than non-Hispanic white women on both the MDS and DQI. Women who were less educated, obese, who smoked and who did not take supplements tended to score lower on measures of dietary quality.

Even after allowing for confounding factors, the researchers found that consuming a high-quality overall diet before pregnancy, measured using either scale, was associated with a significantly reduced risk of birth defects. Women in the top quartile for DQI score were less than half as likely as those in the bottom quartile to have a baby with anencephaly (odds ratio 0.49), and a third less likely to have a baby with cleft lip with or without cleft palate (OR 0.66).

The researchers said: “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.

“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.”

They concluded: “The findings from this study suggest that overall diet quality is more predictive of birth defect risk than intake of single nutrients.”

A commentator on the study wrote: “The importance of [these] findings … lies in showing that women obtain benefit from the consumption of a high-quality diet, beyond the benefits derived through grain fortification. This raises the question of whether a high-quality diet alone may be sufficient to prevent NTDs (neural tube defects) – a strategy that would also remove the potential harm from fortification.

“Reduction of NTDs may be achievable by diet alone, at the same time reducing potential risk for other chronic diseases in the rest of the population.”

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