A healthy diet during pregnancy can reduce the risk of birth defects: Study

By Dr. Ananya Mandal, MDOct 6 2011

A new study shows that women who eat a better diet leading up to pregnancy are less likely to have babies with birth defects.

The researchers say that the birth defects like brain and spine problems, called neural tube defects, as well as cleft lip and cleft palate were less common in mothers who closely followed either a Mediterranean diet or the food guide pyramid.

Suzan Carmichael from Stanford University, who worked on the study said, “A lot of birth defects including neural tube defects occur very early in pregnancy, before women even know they're pregnant… These messages are important for women who are at any risk of becoming pregnant.” The bottom line for women who are pregnant or may get pregnant, she said, is to “eat a variety of foods, including a lot of fruits and vegetables and grains in your diet, and take a vitamin supplement that contains folic acid.”

Grain products have been fortified with folic acid in the U.S. since the late 1990s, when studies found that low levels of folate during pregnancy were linked to brain and spine birth defects. Pregnant women are also recommended to take a prenatal vitamin with folic acid and iron.

Carmichael and her colleagues tried to see if eating a healthy, balanced diet could have the same protective effect as getting extra vitamins and minerals through supplements. They used data from the National Birth Defects Prevention Study to compare about 3,400 women who had a baby with a neural tube defect or a cleft lip or palate and 6,100 women whose babies didn't have a birth defect. Each of those women completed a phone interview in the two years after her baby was born.

Researchers asked the new mothers how frequently they had eaten a range of foods, from beans to candy, in the few months before they became pregnant. Then they calculated how closely women had followed a Mediterranean diet (high in beans, fruits and vegetables, grains and fish and low in dairy, meat and sweets) and the U.S. Department of Agriculture Food Guide Pyramid (high in grains and fruits and vegetables, with few calories from fat and sweets).

After taking into account how much women weighed, whether they took vitamins and if they smoked and drank, Carmichael and her colleagues found that those who more closely followed either healthy diet were less likely to have babies with any of the birth defects they studied.

In particular, women with a diet closely matched to the USDA Food Guide Pyramid were half as likely to have a baby missing part of its brain and skull - a birth defect called anencephaly - than women whose diet was farthest from those guidelines. They were also 34 percent less likely to have a baby with cleft lip and 26 percent less likely to have one with cleft palate.

Epidemiologist David Jacobs, from the University of Minnesota in Minneapolis, said the findings suggest that a healthy diet can lower the risk of birth defects in the same way that has happened through folic acid fortification. “If you are a woman about to become pregnant or think you might become pregnant, it's all the more reason for you to take care of yourself and seek out better foods,” said Jacobs, who wrote a commentary accompanying the study in the Archives of Pediatrics and Adolescent Medicine.

Luz de Regil, from the World Health Organization's Department of Nutrition for Health and Development in Geneva, cautioned that with the current evidence about the benefits of prenatal supplements, a good diet isn't enough during pregnancy. “If a woman is trying to get pregnant, a good diet should be a complement to the use of folic acid supplementation, not a substitute,” said de Regil, who wasn't involved in the new research. “Having a baby (and) a good pregnancy is a result of many things,” she added. Trying to eat a healthy diet, with lots of fruits and vegetables, “totally makes sense.”

“Nutrition research on birth defects has tended to focus on one nutrient (or nutritional factor) at a time,” according to the study. “However, the reality of nutrition is much more complex.” The study concluded, “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."