Kaplan-Meier survival estimates. Error bars indicate 95% CI estimates at intervals of 1, 2, and 3 years. Estimates were obtained from nonparametric maximum likelihood estimation, with optimal nonparametric testing with interval-censored response times. These interval-censored response times lead to gaps in the curves, which we have denoted with diagonal lines. The hazard ratio for the time to first event of asthma or recurrent wheeze was 0.8 (95% CI, 0.6–1.0; P value = .051).