Effect of birthweight on pneumonia-specific and total mortality among infants in the highlands of Papua New Guinea.

A cohort of 1711 children born in Tari, Southern Highlands Province, Papua New Guinea was followed to determine the effect of birthweight on total and cause-specific mortality at varying ages during infancy. Mean birthweight was 3.04 kg, males were significantly heavier than females and first offspring significantly lighter than other offspring. Children weighing < or = 2.5 kg at birth accounted for 15% of all births and 32% of all deaths and were 2.7 times more likely to die in infancy than heavier children. Infant mortality was negatively associated with birthweight (p < 0.001). Mortality was very high among children with birthweight < or = 2 kg and was lowest in the 3.1-3.5 kg birthweight category. Pneumonia mortality declined with increasing birthweight in the 1-5 month age group, but in the 6-11 month age group the risk of death from pneumonia was the same among children with birthweight > 3.5 kg as those with birthweight < or = 2.5 kg. While control of infectious diseases will have a marked impact on infant mortality in the short term, longer-term interventions aimed at improving socioeconomic status are needed to improve nutritional status of both adults and children (including birthweight) and hence sustain the lower mortality levels achieved in young children.