Abstract
Neonatal mortality during the first week of life, corresponding to the years 19750·023 per year. This decline cannot be explained by an increase in the mean birth weight (MBW=23440·835−10·107 g per year). From the most frequent of the causes of death to the least were: congenital anomalies, preterm born or low birth weight, respiratory problems, pregnancy difficulties, hypoxaemia/asphyxia, delivery difficulties and infectious diseases. This sequence changed when the specific age at death was considered. The NMR descended evenly for both sexes for the causes indicated above, except for preterm born or low birth weight, in which the male mortality decrease was greater since its rate was more elevated at the beginning of the period studied. For all the causes listed, NMR was more elevated both in urban areas and for males. Early neonatal mortality (first 24 hours) was higher for pregnancy difficulties, preterm born or low birth weight, congenital anomalies and hypoxaemia/asphyxia