Pregnancy health centre

Babies born to women with healthy diets less likely to have birth defects

By Lilian Anekwe

BMJ Group News

What do we know already?

There has been some research into whether diet can protect against birth defects, but it mostly looked at individual vitamins and supplements. Few studies have looked at the overall benefits of a high-quality diet on birth defects.

Pregnant women are currently advised to take folic acid supplements to help prevent their babies from getting birth defects called neural tube defects. The most common neural tube defects are anencephaly and spina bifida. Spina bifida happens when a baby’s spine does not develop normally. Anencephaly means the brain doesn’t grow properly, and the baby usually dies within a few days of birth.

However, folic acid doesn’t prevent all types of birth defects. We need to know how far the other aspects of a healthy diet play a role in preventing neural tube defects and other birth defects such as a cleft lip or palate.

A study of a large US registry of birth defects compared the diets of more than three thousand women whose babies were born with birth defects with more than six thousand women whose babies were born without defects, to find out if women with a healthier diet were less likely to have babies with birth defects.

The researchers interviewed women after they had given birth about their diet and how often they consumed different foods in the year before they had become pregnant. They compared their answers against two diet quality standards, which gave a higher score for eating healthy foods such as legumes, fruits and nuts, vegetables, fish, and sources of iron and calcium, and negative scores to foods such as meat, dairy products, and high-fat foods.

The researchers calculated an overall score for each woman and ranged them in four groups, from the highest quality to lowest quality diet.

What does the new study say?

Babies born to women who ate a high-quality diet had a lower risk of birth defects, even after the researchers had accounted for other factors that could have affected the results such as ethnicity, whether the women drank alcohol or smoked, their weight, and whether they took folic acid supplements.

Babies of women who scored highest in the Diet Quality Index were 55% less likely to have anencephaly, 28% less likely to have spina bifida, 36% less likely to have a cleft lip, and 23% less likely to have a cleft palate, compared to women with the lowest quality diets.

Previous studies using this same registry of birth defects looked at single nutrients in isolation and produced inconsistent results. But this study suggests that the overall quality of a woman’s diet in the year before getting pregnant is more likely to be linked to a lower risk of birth defects.