The relation between the availability of neonatal intensive care and neonatal mortality

Background: There is marked regional variation in the availability of neonatal intensive care in the United States. We conducted a study to determine whether a greater supply of neonatologists or neonatal intensive care beds is associated with lower neonatal mortality. Methods: We used the 1996 master files of the American Medical Association and the American Osteopathic Association and 1998 and 1999 surveys of neonatal intensive care units to calculate the supply of neonatologists and neonatal intensive care beds in 246 neonatal intensive care regions. We used linked birth and death records from the 1995 U.S. birth cohort to assess associations between the supply of both neonatologists and neonatal intensive care beds per capita (in quintiles) and the risk of death within the first 27 days of life. Results: Among 3,892,208 newborns with a birth weight of 500 g or greater, the mortality rate was 3.4 per 1000 births. After adjustment for neonatal and maternal characteristics associated with an increased risk of neonatal death, the rate was lower in the regions with 4.3 neonatologists per 10,000 births than in those with 2.7 neonatologists per 10,000 births (odds ratio for death, 0.93; 95 percent confidence interval, 0.88 to 0.99). Further increases in the number of neonatologists were not associated with greater reductions in the risk of death. There was no consistent relation between the number of neonatal intensive care beds and neonatal mortality. Conclusions: A minority of regions in the United States may have inadequate neonatal intensive care resources, whereas many others may have more resources than are needed to prevent the death of high-risk newborns. The effect of the availability of neonatologists on other health outcomes is not known.