Maternal multivitamin use and orofacial clefts in offspring

Background: Cleft lip with or without cleft palate (CLP) and cleft palate a lone (CP) affect approximately 1 in 1000 infants and 1 in 2,500 infants, re spectively. Studies of the relation between orofacial clefts and multivitam ins or folic acid have been inconsistent. Methods: We used data from a population-based case-control study involving 309 nonsyndromic cleft-affected births (222 with CLP, 87 with CP) and 3,029 control births from 1968 to 1980 to evaluate the relation between regular multivitamin use and the birth prevalence of orofacial clefts. Results: We found a 48% risk reduction for CLP (odds ratio = 0.52, 95% conf idence interval = 0.34-0.80) among mothers who used multivitamins during th e periconceptional period or who started multivitamin use during the first postconceptional month, after controlling for several covariates. The risk reduction for CP was less than those for CLP (odds ratio = 0.81, 95% confid ence interval = 0.44-1.52); however, a small number of CP cases limited int erpretation. No risk reductions for CLP or CP were found for women who bega n multivitamin use in the second or third month after conception. Conclusions: The magnitude of the risk reduction in our study is comparable to those of other recent studies; our study does not support the contentio n that only large dosages of folic acid are needed to prevent orofacial cle fts. More studies are needed to test the effects of multivitamins and varyi ng dosages of folic acid on the recurrence and/or occurrence of orofacial c lefts to provide information needed to determine possible prevention strate gies.