Antibiotic use in the first year of life and asthma in early childhood.

An association between antibiotic use in early life and asthma in childhood has been reported in five retrospective studies and one longitudinal study. To examine the relation between the use of oral antibiotics in the first year of life and asthma in early childhood. Longitudinal follow-up of 4408 children enrolled in a health maintenance organization (HMO) from birth to the age of 5 years. After adjusting for sex and illnesses of the lower respiratory tract (LRIs), we found a significant association between antibiotic use in the first year of life and asthma between the ages of 1 and 2 years (odds ratio (OR) for 1-2 vs. no courses of antibiotics=1.9, 95% confidence interval (CI)=1.3-2.7; OR for 3-4 vs. no courses of antibiotics=1.6, 95% CI=1.1-2.4; OR for at least 5 vs. no courses of antibiotics=2.1, 95% CI=1.5-3.2). After adjustment for sex and LRIs in the first year of life, there was no significant association between antibiotic use in the first year of life and asthma that was initially diagnosed between the ages of 2 and 5 years and that persisted up to the age of 5 years (OR for 1-2 vs. no courses of antibiotics=1.1, 95% CI=0.8-1.4; OR for 3-4 vs. no courses of antibiotics=1.3, 95% CI=0.9-1.8; OR for at least 5 vs. no courses of antibiotics=1.0, 95% CI=0.7-1.4). Conclusions Our findings do not support the hypothesis that antibiotic use in early life is associated with the subsequent development of asthma in childhood but rather suggest that frequent antibiotic use in early life is more common among asthmatic children.