A growing body of evidence suggests outcomes for cardiac arrest are worse during nights and weekends when compared with daytime and weekdays. Several large registry-based studies of in-hospital cardiac arrest suggest outcomes are worse during nights and weekends when compared with daytime and weekdays [[1], [2], [3], [4], [5]]. In the out-of-hospital setting, emerging evidence indicates similar patterns may be taking place [[6], [7], [8], [9], [10], [11]]. More than one-half of out-of-hospital cardiac arrests in pediatric patients involve infants under 1 year of age [12].

We hypothesize that clinical outcomes for infant out-of-hospital cardiac arrest may vary across time-of-day and day-of-the-week. Given emergency medical services (EMS) are often the first responders to out-of-hospital cardiac arrest in both children and adults, data from the EMS perspective is a valuable tool for examining trends in the incidence, resuscitation, and outcomes of cardiac arrest. In this study, we utilized a large and nationally-representative database of EMS activations to ascertain if there are any differences in infant cardiac arrest outcomes when comparing daytime with nighttime and weekdays with weekends.