Reported multivitamin consumption and the occurrence of multiple congenital anomalies.

The purpose of this case-control study was to determine whether multivitamin use is associated with the occurrence of multiple congenital anomalies (MCA). MCA case-infants were infants with two or more major birth defects affecting at least two different organ systems, with no recognized chromosome abnormality or single gene disorder. Control-infants were a random sample of live births with no major birth defects from the same population (metropolitan Atlanta) and time period (1993-1997) as the case-infants. Exposure to multivitamins, cereals, and supplements was ascertained from a maternal telephone interview and classified based on folic acid content. We compared women who used multivitamins three or more times per week with women who were not exposed to vitamins/cereals/supplements during the periconceptional period (3 months before pregnancy through the first trimester), adjusting for maternal age, education, race/ethnicity, first degree family history of a major birth defect, pre-pregnancy maternal body mass index, gravidity, and first trimester alcohol use and cigarette smoking. Periconceptional multivitamin use was associated with MCA among all infants (adjusted odds ratio [aOR]=2.4, 95% confidence interval [CI] 0.9-6.7), and especially when analysis was limited to those with no family history of major defects (aOR=4.0, 95% CI 1.3-12.8). MCA-infants with urinary obstructive defects were more common among multivitamin-exposed infants than among unexposed infants, but this defect did not occur within a consistent pattern of defects. While these findings provide some support for one previous study, the interpretation remains unclear given the proven protective effect of multivitamins containing folic acid on isolated neural tube defects and possibly other types of defects.