Ethnic variation in oral cleft occurrence in denmark 1981-2002.

Objective : To examine differences in oral cleft (OC) occurrence based on maternal only and parental country of origin in Denmark from 1981 to 2002. Methods : Data on all live births from the Danish Medical Birth Register from 1981 to 2002 were linked with the Danish Facial Cleft Database. Cleft cases were categorized into isolated and nonisolated cleft lip with or without palate (CL/P) and cleft palate only (CP). Birth prevalence was calculated as cases per 1,000 live born children by maternal country of origin, world region, and mixed parental groups. Results : We identified 3094 OC cases among 1,319,426 live births. Danish-born women had an OC birth prevalence of 2.38 with a 95% confidence interval (CI) (2.29-2.47) and foreign-born women a significant lower prevalence of 2.01 (CI, 1.77-2.27). This difference was explained by a lower isolated CL/P birth prevalence among foreign-born women of 0.97 (CI, 0.81-1.16) versus 1.35 (CI, 1.28-1.41). No significant differences were seen for the remaining subtypes. Parents with the same foreign country of origin had a lower overall OC (1.63; CI, 1.35-1.94) and isolated CL/P (0.76; CI, 0.57-0.99) birth prevalence than Danish-born parents. This was not the case for any of the mixed parental groups. Overall and subtype prevalence rates varied according to maternal categories of world region. Conclusion : In this study we found differences in OC occurrence among all live births in the Danish population based on maternal country of origin from 1981 to 2002. Danish-born women had higher OC and isolated CL/P birth prevalence compared with foreign-born women.