Epidemiology of facial clefts.

Data from the Glasgow Register of Congenital Malformations were used to investigate the epidemiology of congenital facial clefts over the period 1974-85. Facial clefts were registered in 247 infants representing a prevalence of 1.56 per 1000 total births. Cleft palate was more common than cleft lip, with cleft lip and palate occupying an intermediate position. More than half of the infants with facial clefts had associated defects. Males predominated for cleft lip; females for cleft palate. Cleft lip (alone) was more common in babies born to women aged 35 years and over. Sudden declines in registered prevalence were observed in 1978 and 1985. Clefts were more common in socioeconomically deprived areas of the city. In comparison with data from elsewhere, Glasgow seems to have a low rate of cleft lip, a high rate of cleft palate, and a high rate of associated defects. Many of the findings of cleft palate in Glasgow could be explained by the interaction of an unidentified environmental teratogen with a susceptible population.