Do multivitamin supplements attenuate the risk for diabetes-associated birth defects?

OBJECTIVE To evaluate whether the risk for birth defects associated with maternal diabetes is attenuated by use of multivitamin supplements during the periconceptional period. METHODS In the population-based Atlanta Birth Defects Case-Control Study, we identified case infants who had nonsyndromic birth defects that were reported to be associated with diabetes (n = 3278) and were born during 1968-1980 to residents of metropolitan Atlanta. Controls were infants without birth defects (n = 3029). Maternal diabetes was defined as reported diabetes with onset before the date of birth of the index infant, and periconceptional use of multivitamins was defined as reported regular use of multivitamin supplements from 3 months before pregnancy through the first 3 months of pregnancy. RESULTS Offspring of mothers with diabetes had an increased risk for selected birth defects. However, the increased risk was limited to offspring of mothers who had diabetes and had not taken multivitamins during the periconceptional period (odds ratio: 3.93; 95% confidence interval: 1.79-8.63). Offspring of mothers who had diabetes and had taken multivitamins during the periconceptional period had no increased risk for birth defects (odds ratio: 0.15; 95% confidence interval: 0.00-1.99). CONCLUSIONS Periconceptional use of multivitamin supplements may reduce the risk for birth defects among offspring of mothers with diabetes.