Objectives: The evidence linking low levels of folic acid and orofacial clefting (OFC) is presently equivocal. There is stronger evidence for the role of folic acid supplementation in protection against the occurrence and recurrence of neural tube defects. The present investigation tested the hypotheses that cleft lip, cleft palate, or both are inversely associated with maternal intake of dietary and supplemental vitamins during the periconceptional period and first 4 months of pregnancy in a Brazilian population.
Design: A population-based, case-control study of cleft lip with or without cleft palate (CL(P)) and isolated cleft palate (CP) in a Brazilian population. In structured interviews, case histories were taken from the mothers of a consecutive sample of 450 infants born with nonsyndromic OFC.
Results: Mothers who had children with CL(P) were less likely to have been supplemented during the periconceptional period. The statistical significance of the difference in prevalence of the use of supplements between mothers of patients and of controls was greater for the CL(P) group: p < .05 for CP and p < .001 for CL(P). Multivariate analysis confirmed this finding of a protective effect for both types of orofacial cleft.
Conclusions: The use of vitamin supplements in the first 4 months of pregnancy was suggestive of a protective effect against the occurrence of CP and CL(P) in this population. The significance of an association between multivitamin supplementation and OFC and the possible role of gene/environment interaction are discussed.