Women who eat healthier diets in the year leading up to pregnancy may reduce the risk of their babies developing heart problems, according to a study published online Aug. 24 in Archives of Diseases in Childhood (Fetal & Neonatal Edition).

Researchers drew on data from the National Birth Defects Prevention Study at 10 sites in the U.S. from 1997 through 2009. Included were 9,885 mothers of babies with nonsyndromic congenital heart defects and 9,468 mothers with unaffected babies. To assess diet, researchers used the Mediterranean Diet Score and the Diet Quality Index for Pregnancy.

The study team, including lead author Lorenzo Botto, MD, division of medical genetics, department of pediatrics, University of Utah, Salt Lake City, found mothers who followed healthier diets reduced by 37% risk of tetralogy of Fallot, which can lead to dangerously low oxygen levels in the blood.

In addition, healthier diets were associated with a 23% reduced risk of atrial septal defects, or holes in the wall of the septum that divides the left and right atria.

“The more you went up in diet quality, the less the risk for severe congenital heart anomalies,” Botto said in an online article published Aug. 25 in HealthDay News.

For other major congenital heart defects, the link to diet was either weaker or minimal, according to the study.

Background information in the study noted that congenital heart defects affect 1 in 100 newborns in the U.S. and cause 1 in 4 birth defect-related deaths. “They are common, they are critical and we really don’t know how to prevent them,” Botto said in HealthDay. “We know that birth defects happen in the very first weeks after conception. For heart anomalies, the first four to seven weeks.”