Outcomes of regionalized perinatal care in Washington State.

We evaluated the extent to which the regionalization of perinatal care in Washington State has succeeded in concentrating high-risk pregnancies in technologically appropriate referral centers and in reducing differences in neonatal outcome among hospitals. Of all infants weighing less than 1,500 grams born between 1980 and 1983, nearly 68% were delivered in level III hospitals, although only 24% of all babies are born in these hospitals, indicating that the state is highly regionalized. Neonatal outcomes-as measured by standardized mortality ratios-are similar in level I, II and III hospitals and are not greatly influenced by the rural or urban location of the hospital. The most promising strategy for further reducing neonatal mortality is to decrease the number and proportion of very-low-birth-weight births.