Postneonatal mortality in a cohort of very low birthweight infants.

A cohort of very low birthweight (VLBW) infants (ie, less than 1500 g) who were admitted to the newborn unit, Waikato Hospital between 1984 and 1988 were followed to the age of 12 months. Four hundred and twenty-five infants were admitted with 385 surviving the neonatal period. A further 29 infants died in the postneonatal period (68.2 per 1000 livebirths). Sixteen of the infants died during their initial hospitalisation - primarily from complications of prematurity, while the remaining 13 died following discharge from hospital (9 from sudden infant death syndrome). The postneonatal mortality rate was 3-5 fold greater than that described in similar studies, reflecting the generally increased rate in New Zealand and a lower neonatal mortality rate. The duration of mechanical ventilation was associated with an increased risk of postneonatal death, but no risk factors for posthospital discharge death could be identified.