Perinatal outcome in Western Australia, 1968 to 1976. Perinatal mortality and birthweight.
Trends in perinatal mortality and low birth-weight in Western Australia were analysed by means of a linked file of perinatal death and birth registration papers for the years 1968 to 1975. Stillbirth rates fell only slightly, and there was no improvement in low birthweight stillbirth rates. There was increased ascertainment of low birthweight stillbirths after 1968 when the definition changed. Neonatal mortality fell markedly after 1971, much of the fall being due to a shift in the birthweight distribution towards heavier babies, particularly in males. The proportion of babies with birthweights of less than 2500 g fell from nearly 6% to 5.3%. The impact of changes in the obstetric care of premature labour were minimal up to 1975, with rural (away from specialist care) low birthweights rates differing only slightly from metropolitan rates. Social and demographic differences probably account for the major differences in stillbirth rates between areas. Neonatal mortality rates in low birthweight babies showed a definite advantage for babies living close to neonatal intensive care facilities. However, decisions to expand neonatal intensive care facilities to rural areas need to take into account other adverse perinatal risk factors.