Eating well before pregnancy linked to lower birth defect risk

Higher maternal diet quality in the year before pregnancy was associated with lower risk for neural tube defects, the study found. Flickr/Aldo Risolvo

Women who stick to a healthy diet in the year before falling pregnant may be less likely to have a baby with birth defects, a new study has found.

Doctors have long counseled pregnant women to consider taking multi-vitamins containing folic acid to reduce the risk of neural tube defects (NTDs) like spina bifida and many foods sold in Australia are fortified with folate additives.

However, a new study of nearly 10,000 women led by Stanford University in the US and published today in the journal Archives of Pediatrics & Adolescent Medicine, found that overall diet was more important than taking individual supplements and that women should start eating well long before falling pregnant.

“Higher maternal diet quality in the year before pregnancy was associated with lower risks for neural tube defects and orofacial clefts (cleft palate). This finding persisted even after adjusting for multiple potential confounders such as maternal intake of vitamin/mineral supplements,” the paper said.

“Similarly, maternal supplement intake was not associated with reduced risk of orofacial clefts, and findings did not suggest associations with multiple dietary nutrients that were examined, including folate.”

“Thus, the findings from this study suggest that overall diet quality is more predictive of birth defect risk than intake of single nutrients.”

The researchers examined data from the US National Birth Defects Prevention Study collected in 10 states on women who expected to give birth between October 1997 and December 2005.

Data on diet was collected via interviews and food questionnaires completed by 936 women whose babies had neural tube defects (291 with anencephaly and 645 with spina bifida) and 2475 with orofacial clefts. A control group of 6147 healthy babies was also included in the study.

The ‘healthiness’ of the maternal food intake was determined by comparing the mothers’ diet with the Mediterranean Diet (Mediterranean Diet Score) and the U.S. Department of Agriculture Food Guide Pyramid (Diet Quality Index).

The researchers said their 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 (meaning preconception) multi-vitamin use.”

An editorial by public health expert David R. Jacobs, from the University of Minnesota published in the same edition of the journal further downplayed the role of folic acid supplements, saying that recent studies suggested they may not be good for older adults.

“The implication, based on many clinical trials of supplements, is that supplementation and its hidden partner in food, fortification, may have some dangers,” the editorial said.

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

Dr Murray Smith, an expert on fetal development from the University of NSW’s School of Medical Sciences, said the personal and financial effects of birth defects must not be underestimated.

“The importance of natural folate intake and green vegetable intake are so important in avoiding birth defects, especially neural tube defects and skeletal malformations but the importance of the effects of folate additives should not be ignored,” he said.

“The good aspect of this research is that it is going to open up the debate about healthy diets.”