Early childhood mortality in a Brazilian cohort: the roles of birthweight and socioeconomic status.

The deaths of children aged 1-4 years were studied in a cohort of 5914 Brazilian liveborns. A total of 29 early childhood deaths were recorded (cumulative mortality risk of approximately 6 per 1000), 17 of which (59%) were due to infectious diseases. The death rate was highest in the second year. Deaths were highly concentrated in children from low income (< US $50/month) families, where the cumulative risk of early childhood death was about 10 per 1000; on the other hand, there were no deaths among the 616 children from families with a monthly income of US $300 or more. Birthweight was also associated with mortality: the cumulative risk of children weighing less than 2000 g at birth was 21 per 1000, compared to 4 per 1000 among those with birthweights of 3500 g or more. Simultaneous adjustment for income and birthweight did not substantially change these differentials. These findings confirm the strong association between early childhood mortality and socioeconomic conditions, but also make evident the long-term effects of low birthweight.