Neonatal mortality in weekend vs weekday births.

CONTEXT: Increases in neonatal mortality for infants born on the weekend were last noted several decades ago. Although the current health care environment has raised concern about the adequacy of weekend care, there have been no contemporary evaluations of daily patterns of births, obstetric intervention, and case mix-adjusted neonatal mortality.

OBJECTIVE: To compare the neonatal mortality of infants born on weekdays and weekends.

DESIGN, SETTING, AND PARTICIPANTS: Case series of 1 615 041 live births (weight >or=500 g) in California between 1995-1997 to determine patterns of births, cesarean deliveries, and neonatal deaths. Analyses were stratified by birth weight and delivery method. To assess the role of weekend differences in case mix, observed and birth weight-adjusted odds ratios (ORs) for increased weekend mortality were estimated using logistic regression.

MAIN OUTCOME MEASURE: Birth weight-adjusted neonatal mortality.

RESULTS: There was a 17.5% decrease in births on weekends, accompanied by a decrease in the proportion of cesarean deliveries from 22% on weekdays to 16% on weekends. Weekend decreases in births were least pronounced in smaller infants, resulting in a weekend concentration of high-mortality, very low-birth-weight (