Low-carb diets boost risk for serious birth defects

TUESDAY, Jan. 30, 2018 -- Having a baby? Don't skimp on carbs.

Following a low-carbohydrate diet during pregnancy may increase a woman's risk of having a baby with serious birth defects, a study by researchers at the University of North Carolina at Chapel Hill suggests.

Compared with pregnant women who didn't restrict their carbohydrate intake, those on a diet that reduced or eliminated carbs were 30 percent more likely to have babies with neural tube defects. Those include spina bifida (spine and spinal cord malformations) and anencephaly (missing parts of the brain and skull).

These birth defects can cause death or lifelong disability, the study authors said.

"We already know that maternal diet before and during early pregnancy plays a significant role in fetal development. What is new about this study is its suggestion that low carbohydrate intake could increase the risk of having a baby with a neural tube defect by 30 percent," study leader Tania Desrosiers said in a university news release.

"This is concerning because low-carbohydrate diets are fairly popular," she explained. Desrosiers is a research assistant professor of epidemiology in UNC's School of Global Public Health.

"This finding reinforces the importance for women who may become pregnant to talk to their health care provider about any special diets or eating behaviors they routinely practice," she added.

An essential nutrient called folic acid (vitamin B9) is known to reduce the risk of neural tube defects. This study found that dietary intake of folic acid among pregnant women on low- or no-carb diets was less than half that of women who didn't limit carbohydrates.

All women who plan to become pregnant should take a daily multivitamin with at least 400 micrograms of folic acid before and during pregnancy, according to the U.S. Centers for Disease Control and Prevention.

Since nearly half of pregnancies in the United States are unplanned, many women may not take the supplements until later in pregnancy, after a neural tube defect might have occurred.

However, the study authors pointed out that, in the United States, folic acid is added to enriched grain products, which can be an important source of the nutrient for women who may become pregnant.

According to the American Pregnancy Association, good dietary sources of folic acid include leafy green vegetables, such as spinach; citrus fruits, such as orange juice; beans; and fortified breads, cereals, rice and pasta.

The study was published Jan. 25 in the journal Birth Defects Research.

More information

The March of Dimes has more on neural tube defects.