Controlled studies of multivitamin supplementation on pregnancy outcomes.

The Hungarian Family Planning Program includes a randomized prospective blind study of periconceptional multivitamin and trace element supplementation to test the efficacy of this treatment in the reduction of the first occurrence of neural tube defect. This program is appropriate for the evaluation of pregnancy outcomes in general. Periconceptional multivitamin supplementation had no beneficial effect on fetal death, that is, chemical and ectopic pregnancies, missed miscarriages, miscarriages, and stillbirths. The proportion of low birth weight (5.8%) was higher in the combined vitamin I-II sample than in the combined trace element I-II sample (4.3%), but it was explained by a higher rate of multiple births in the vitamin sample. The estimated rate of monozygotic twins was higher after periconceptional multivitamin supplementation. The number of informative pregnancies using vitamin and trace elements was 2104 and 2052, respectively. The rate of cases with congenital abnormality was significantly higher in the total trace element sample (22.4 per 1000) than in the total vitamin sample (13.3 per 1000).