[Probability of dying in the first year of life in an urban area of southern Brazil].

A birth-cohort of 4,876 children born alive in hospital were selected and followed through up to the age of one year with a view to estimating the risk of dying in the first year of life. All of them were born in 1989, in one of the seven hospitals of an urban area of Southern Brazil and the only requirement for belonging to the cohort was that of residence on the area. The selected variables were: sex, birthweight, age at moment of death, underlying cause of death, and maternal age. The estimated probability of dying in the first year was of 19.9 per 1,000 (77.3% of the deaths occurred during the neonatal period). Perinatal causes and congenital malformations contributed to 80% of the deaths, and infectious diseases were the underlying cause of death in only 1.1% of the losses. The risk of dying in the first year of life due to afections arising during the perinatal period was higher among vaginally delivered babies (20.3 per 1,000) than it was for those born by cesarean section (9 per 1,000). A higher probability of death was present among infants born to adolescent mothers, and those with low birthweight (less than 2,500g). The results brought out the need for improving the quality of prenatal and infant care. They also suggested the hypothesis of a possible association between higher infant mortality and lower socio-economic level.