Neonatal death rates are higher after evening and late night deliveries than after daytime deliveries, according to a report by researcher in California.

“The problem most likely represents a mismatch between the clinical demands that arise at night and a hospital’s capacity to deal with these demands,” said Dr. Jeffrey B. Gould from Stanford University, Palo Alto.

Gould and his associates used data from linked birth-death certificates for more than 3 million infants in California to investigate the influence of time of birth and the risk of neonatal death.

Overall, neonatal mortality was 2.08 deaths per 1000 live births, the team reports in the medical journal Obstetrics & Gynecology. The death rate was lower for daytime births (1.88 per 1000 live births) than for early night (2.37 per 1000 births) and late night (2.31 per 1000 live births) births.

Even after adjusting for adequacy of prenatal care, complications of pregnancy, gender, and birth weight, neonatal mortality was 12 percent higher for infants born in the early night and 16 percent higher for infants born late at night, the report indicates.

“The increase in deaths to infants born at night is not a uniquely California problem,” Gould said. “Even in Sweden, noted for its excellent health care system, it was estimated that 12 percent of early neonatal deaths could be attributed to an increased rate of death in infants born at night,” he pointed out.

“It is possible that part of the increase in mortality is that infants born at night have risk factors that were not identified in this study,” Gould said. “Nevertheless, in addition to more research, at a practical level we feel that time of birth and its attendant factors should be incorporated into the hospital perinatal mortality review process.”

SOURCE: Obstetrics & Gynecology, August 2005.