Correlation of decrease in perinatal mortality and increase in cesarean section rates.

During what has proved to be a critical period in the practice of modern obstetrics, 1965 to 1980, when cesarean birth rates increased dramatically in centers across the United States from less than 5 to more than 15%, the number of infants born in the National Maternity Hospital, Dublin, was 108,987. Although the incidence of cesarean section remained virtually unchanged at 4.2, 4.2, 4.2, and 4.8% in 1965, 1970, 1975, and 1980, respectively, perinatal mortality continued to fall from 42.1 to 36.5, 24.0, and 16.8 per 1000 infants born at 500 g or more. These results do not support the contention that the expansion in cesarean birth rates has contributed significantly to reduced perinatal mortality in recent years. Consideration of indications shows that the threefold difference in cesarean birth rate which now exists between Dublin and similar centers across the United States can be accounted for almost entirely by a different approach to management of labor in nulliparous women, compounded by rigid adherence to precept "once a section, always a section.