Epidemiology of cleft palate alone and cleft palate with accompanying defects.

The epidemiology of cleft palate with multiple defects is often thought to be different from that of cleft palate alone, but there are few empirical data on this question. We explored this in a population-based data set created by combining data from two sources: the 1.8 million live births recorded from 1967 to 1998 in the Norwegian Birth Registry, and the two Norwegian surgical centers that repair cleft palate. Accompanying defects were identified from either source. Stratified analysis and logistic regression were used to assess relative risks by covariates. Of 1,431 babies with cleft palate, 31 % had another birth defect recorded by one or both sources. Prevalence of isolated cleft palate was steady over time, while cleft palate with other defects increased substantially. Girls had a higher risk of isolated cleft palate (relative risk 1.4; 95% confidence interval, 1.2-1.6) but not of cleft palate accompanied by other defects (1.1; 0.88-1.3). Older parents and parents who were first cousins had no increased risk of isolated cleft palate, but were twice as likely as others to have a baby with cleft palate accompanied by other defects. Risk factors differ between cases of cleft palate with and without accompanying defects.