Objective: To study the human teratogenic risk of a folic acid-containing multivitamin.
Methods: We evaluated the data set of two Hungarian intervention studies: a randomized double-blind, controlled trial and a two-cohort, controlled study of the same folic acid-containing multivitamin in participants of the Hungarian periconceptional service.
Results: Of 2471 supplemented and 2391 unsupplemented women, 18 and 21, respectively, had multiple congenital abnormalities in the randomized, controlled trial. Of 3056 supplemented and unsupplemented pairs in the two-cohort, controlled study, 33 and 32, respectively, were affected with multiple congenital abnormalities. After the combination of two data sets, the number of cases with multiple congenital abnormalities was 51 in the supplemented group and 53 in the unsupplemented group (odds ratio 0.89; 95% confidence interval 0.45, 1.68). In addition, there was no difference in the occurrence of specified multiple congenital abnormality entities or of unidentified multimalformed informative offspring.
Conclusion: We found no evidence that periconceptional folic acid-containing multivitamin supplementation either prevents or induces multiple congenital abnormalities.