Periconceptional folic acid and multivitamin supplementation for the prevention of neural tube defects and other congenital abnormalities.

The pioneering studies of Smithells et al. showed the reduction of recurrent neural-tube defects (NTD) after periconceptional folic acid-containing multivitamin supplementation. The Hungarian Periconceptional Service was established in 1984, and this primary health care system offered a chance to organize a randomized controlled trial to check whether the supplementation of a multivitamin containing 0.8 mg of folic acid during the periconceptional period is appropriate for the reduction of a first occurrence of NTD in the family. This found a reduction of approximately 90% of primary NTD. An unexpected finding was a significant reduction in the rate of congenital abnormalities overall: 20.6 per 1000 in the 'multivitamin' group, and 40.6 per 1000 in the 'trace-element-like' placebo group (RR = 0.53, 95% CI: 0.35-0.70). When the 6 cases of NTD were excluded, this difference in the rates of major congenital abnormalities between the two study-groups remained very highly significant (p < 0.0001). Cardiovascular malformations and urinary tract defects were particularly affected. These findings were confirmed in the Hungarian cohort-controlled trial and by observational studies in other countries. Two questions remain to be answered. Is folic acid better alone or with multivitamins? What is the optimal dose of folic acid? Overall, the Hungarian experiences of periconceptional care have shown not only primary prevention of several severe congenital abnormalities but also a good cost-benefit balance. (c) 2009 Wiley-Liss, Inc.