This study estimates the effect of maternal infections during pregnancy on childhood asthma. One-thousand four-hundred and twenty-eight pregnant women were prospectively followed using structured interviews and chart review until their child's 6th year of life. Infections were identified from outpatient and hospital visits. Childhood asthma was defined as physician diagnosis with symptoms at age six. Adjusted odds ratios were calculated from multivariable logistic regression models. Six-hundred and thirty-five women experienced an infection during pregnancy. Among antepartum infections, maternal urinary tract infections were significantly associated with childhood asthma (aOR 1.60, 95 % CI 1.12-2.29). Chorioamnionitis and maternal group beta streptococcus colonization were not significantly associated with an increased risk in childhood asthma. This study found an increased risk of asthma in children of women diagnosed with urinary tract infections during pregnancy, while other maternal infections did not increase the risk.