Omand JA, et al. - In this prospective cohort study, experts aspired to explore whether vitamin D serum levels in early childhood were linked with health service utilization (HSU) for asthma including hospital admissions, Emergency Department visits and outpatient sick visits as well as ascertain if vitamin D supplementation in pregnancy or childhood were correlated with HSU for asthma. Between 2008 and 2013, children participating in the TARGet Kids! practice-based research network in Toronto, Canada were involved. They used multivariable quasi-Poisson and logistic regression to assess the relationship between 25-hydroxyvitamin D concentrations, vitamin D supplementation in pregnancy, and childhood and HSU for asthma. In this population of healthy urban children, vitamin D blood values did not seem to be related with HSU for asthma.