Periconceptional multivitamin use and the occurrence of conotruncal heart defects : Results from a population-based, case-control study

The preventive efficacy of the periconceptional use of multivitamins is well established for neural tube defects, much less so for other birth defects. We conducted a population-based, case-control study to assess the effects of multivitamin use on the risk for conotruncal defects, a group of severe heart defects that includes transposition of the great arteries, tetralogy of Fallot, and truncus arteriosus. From the population-based Atlanta Birth Defects Case-Control Study, we identified 158 case infants with conotruncal defects and 3026 unaffected, randomly chosen control infants, born from 1968 through 1980 to mothers residing in metropolitan Atlanta. Periconceptional multivitamin use was defined as reported regular use from 3 months before conception through the third month of pregnancy. We present the results of the crude analysis, because the multivariate model yielded essentially identical results. Mothers who reported periconceptional multivitamin use had a 43% lower risk of having infants with conotruncal defects (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.33 to 1.00) than did mothers who reported no use. The estimated relative risk was lowest for isolated conotruncal defects (OR, 0.41; 95% CI, 0.20 to 0.84) compared with those associated with noncardiac defects (OR, 0.91; 95% CI, 0.33 to 2.52) or a recognized syndrome (OR, 1.82; 95% CI, 0.31 to 10.67). Among anatomic subgroups of defects, transposition of the great arteries showed the greatest reduction in risk (OR, 0.36; 95% CI, 0.15 to 0.89). Periconceptional multivitamin use is associated with a reduced risk for conotruncal defects. These findings could have major implications for the prevention of these birth defects.