The prevalence at birth of cogenital malformations at a maternity hospital in Osaka City, 1948-1990.

The frequencies of congenital malformations at St. Barnabas' Hospital, Osaka were studied during the period 1948-1990. There were 1,418 malformed infants diagnosed during the first week of life among a total number of 131,996 births during the period. Of the 1.07% of malformed children, 0.90% had single and 0.17% had multiple malformations. The birth prevalence was 1.07% in singletons and 1.20% in twins. There was significant difference in prevalence between males (1.15%) and females (0.97%). The prevalence was 0.88% for the period 1948-1958 and increased with each year cohort up to the recent period when the value was 1.38%. Varus deformities of feet was the most common defect (23.4 per 10,000 births), followed by polydactyly (finger) (7.8), anencephaly (7.1), cleft lip and palate (6.5), syndactyly (toe) (6.5), cleft lip (6.3), and Down's syndrome (6.1). The prevalence of conjoined twins was 1 in 65,551 deliveries. Significant differences occurred between males and females for cleft palate, cleft lip and palate, syndactyly (finger), oligodactyly (finger), and hypoplastic auricle. The prevalences for valgus deformities of feet, syndactyly (toe) and atresia ani increased significantly with the year cohort, whereas the prevalence of cleft palate decreased significantly with the year cohort. Overall prevalence was significantly higher in 1970-1990 (1.28% than in 1948-1969 (0.88%). Similar results were examined for cleft lip and palate, syndactyly (finger), syndactyly (toe), hypospadias, hydrocele testis, and Down's syndrome.