Antibiotic use during the first 200 days of life.

To examine the use of antibiotics by infants in eastern Iowa, longitudinal data were collected from a cohort recruited at birth from 8 hospitals. Parents of recruited children were mailed questionnaires 6 weeks, 3 months, and 6 months after birth. Cumulative rates of use were determined by means of life tables for any antibiotic as well as by type of antibiotic. Factors associated with antibiotic use and patterns of use were also determined. There were data for 789 children. Antibiotic use was common in our cohort and increased with age. At 50, 100, 150, and 200 days of life, 8.7%, 26.7%, 37.3%, and 70.5%, respectively, of the infants had used at least 1 antibiotic. Infants were most frequently treated with amoxicillin, followed by cephalosporins and sulfonamides. Otitis media was the illness that most commonly prompted the use of an antibiotic.