Infant mortality in southern Brazil: a population based study of causes of death.

The causes of 215 infant deaths occurring in a population based cohort of 5914 infants from southern Brazil were determined. Perinatal problems were responsible for 43% of these deaths and infectious diseases for 32%. In the group who died of infectious diseases, respiratory infections and diarrhoea were equally important, each accounting for 12% of all deaths. A total of 87% of the deaths occurred in the first six months of life, and this proportion remained high (77%) even after perinatal causes had been excluded. On the other hand, 53% of the infants who died were of low birth weight, as opposed to 7.9% of the survivors. This suggests that low birthweight infants need to be carefully followed by health workers at primary level, especially during the first six months. It was estimated that if the incidence of low birth weight was reduced from the present 8.8% to 5% the likely reduction in infant mortality would be 20%. This reduction would be 33% for deaths due to perinatal causes, 14% for respiratory infections, and only 5% for diarrhoea. Efforts for the prevention of infant deaths in southern Brazil are more likely to be effective if they concentrate on improving perinatal health care and environmental conditions.