A study of etiologic factors for cleft lip and palate in Sri Lanka.

Fifty-eight infants with cleft lip and/or cleft palate detected in a prospective study and 443 cleft patients in a retrospective study were investigated regarding seasonal variation of incidence, relation to birth rank, consanguinity of parents, and history of viral infections and drugs taken by mothers during the first trimester of gestation. The highest incidence was recorded in the month of April, but no reason for this could be found. No significant relation to birth rank and consanguinity of parents existed. Furthermore, the proportion of mothers of cleft patients who had taken drugs or who had viral infections was not significantly greater than in the control groups. These findings support the view that orofacial clefts probably have a multifactorial etiology.