Volume 47 | Number 4 | August 2012

Abstract List

George L. Wehby Ph.D., Jorge Lopez‐Camelo, Eduardo E. Castilla


To assess the effects of hospital volume of very low‐birthweight () infants on in‐hospital mortality of and very preterm birth () infants in outh merica.

Data Sources/Study Setting

Birth‐registry data for infants born in 1982–2008 at or very preterm in 66 hospitals in rgentina, razil, and hile.


Regression analyses that adjust for several individual‐level demographic, socioeconomic, and health factors; hospital‐level characteristics; and country‐fixed effects are employed.

Data Collection/Extraction Methods

Physicians interviewed mothers before hospital discharge and abstracted hospital medical records using similar methods at all hospitals.

Principal Findings

Volume has significant nonlinear beneficial effects on and in‐hospital survival. The largest survival benefits––more than 80 percent decrease in mortality rates––are with volume increases from low to medium or medium‐high levels (from ≤25 to 72 infants annually) with significantly lower incremental benefits thereafter. The cumulative volume effects are maximized at the 121–144 annual infant range––about 90 percent decrease in mortality rates compared to <25 infants annually.


Increasing the access of pregnancies at‐risk of and to medium‐ or high‐volume hospitals up to 144 infants per year may substantially improve in‐hospital infant survival in the study countries.