Population studies in northern Sweden

Abstract

The frequency of oral clefts, polydactyly, syndactyly and club foot was studied in the county of Vasterbotten in northern Sweden in a series of 61.061 live births during the period 1950–1973. A total of 280 malformations (4.6 per 1000 births) were registered. The frequency of all malformations and particularly of syndactyly increased after 1965. These time trends are probably to a large extent due to an increased observance after the introduction of the national register of congenital malformations. The frequencies of all malformations except cleft palate were in agreement with the figures found in previous investigations. The frequency of cleft palate was 2–3 times higher than in southern Sweden. Women from the inland area, who were delivered at the university hospital, had an increased frequency of malformed children compared to women delivered at the local hospital. A significantly increased frequency of malformations was found in 2 out of 14 regions studied. These two regions were located in the inland area and not in the urbanized and polluted parts of the coastal area. In contrast to other investigations the sex ratio was found to be normal in club foot. Among infants with cleft palate a significant excess of mothers over 34 years of age was found.