Objective. We assessed the epidemiology of neonatal infections coming to medical attention among inpatient and outpatient newborn infants within a defined health care maintenance organization (HMO) population.
Design and methods. This was a retrospective cohort study, using automated data from a large health maintenance organization and the hospital where the majority of HMO patients delivered. All infants delivered between October 1, 1990 and March 31, 1998 at the study hospital and receiving postdischarge care at the study HMO for the first 30 days of life were included. The outcomes assessed were 10 neonatal infection syndromes defined according to modified National Nosocomial Infection System criteria.
Results. There were 13 224 infants in the study cohort. Of these, 559 infants (4.2%) had 574 infections. Nonpneumonia respiratory infections were most common, accounting for 43% of all infections. Infections diagnosed in the outpatient setting comprised 63% of all infections. More serious infections (bloodstream infection, clinical sepsis and pneumonia) were typically diagnosed in the first few days of life and before nursery discharge. Infants with an infection had a significantly longer length of nursery stay (4.7 excess days among full term infants, P < 0.001), more office visits (397.3 vs. 273.3 per 100, P < 0.001) and more hospital admissions (16.7 vs. 3.6 per 100, P = 0.001) than uninfected infants.
Conclusion. Infections were common during the first 30 days of life. The majority were noninvasive, were diagnosed in the outpatient setting and were most likely community-acquired. Serious infections were rare, occurred early in the neonatal period and were usually diagnosed before nursery discharge.