Neonatal herpes morbidity and mortality in California, 1995-2003

Background: Neonatal herpes infections can have serious consequences. Methods for monitoring the incidence of neonatal herpes have not been standardized. Objectives: To use existing data to examine neonatal herpes-related morbidity in California. Methods: California hospital discharge and mortality data were used to identify neonatal herpes cases, defined as a herpes-related discharge diagnosis with an admitting age of 42 days or less, and neonatal herpes-related deaths. California birth data were used to identify pregnancies complicated by herpes and to determine cesarean section rates. Results: The overall incidence of neonatal herpes was 12.1 per 100,000 live births per year, with no observable change from 1995 to 2003. Neonatal herpes-related mortality, which was estimated to be 0.8 deaths per 100,000 live births, also did not show significant change over time. Between 1995 and 2002, herpes complication in labor declined steadily from 0.23% to 0.09% of all labors (P <0.0001). Among pregnancies with herpes as a complication of labor, cesarean section rates increased from 72.2% to 78.3% (P = 0.01), whereas overall cesarean rates increased from 20.0% to 26.0% (P <0.0001). Conclusions: Existing data can be used to monitor the morbidity and mortality of neonatal herpes. Because the rate of neonatal herpes cases and deaths was stable from 1995 to 2003 despite a decrease in herpes complications in labor and an increase in cesarean rates, new interventions are needed to prevent neonatal herpes.