Background Child passenger safety continues to be a high priority for protecting children both in the US and globally. Children ages 4–7 are often moved to an adult lap belt prematurely, significantly increasing their risk in a crash. Mobile apps offer an efficient and potentially effective way to deliver personalized, tailored, and persuasive messages, and may help parents use the correct restraint.

Objectives This study evaluates Safety in Seconds v2.0TM, a theory-based mobile app designed to address four components of proper and consistent car seat use: 1) having the correct restraint for the child’s age and weight; 2) having the child ride in the backseat all the time; 3) buckling up the child all the time; and 4) having the child’s restraint inspected by a child passenger safety technician.

Methods We conducted an RCT in pediatric emergency departments in Baltimore, Maryland and Little Rock, Arkansas with 742 parents of children 4–7 years old. The intervention group received the child passenger safety information, and the control group received attention matched information about fire safety. Baseline, 3 month, and 6 month surveys were completed. Data were analyzed using conditional logistic regression models, adjusting for baseline behaviors and attrition.

Findings The intervention group was significantly (p<0.05) more likely to report: using the correct car seat at both 3 months (OR=2.073) and 6 months (OR=1.836); having the child ride in the back seat only at 3 months (OR=2.371); and having the car seat inspected at both 3 months (OR=1.990) and at 6 months (OR=1.730).

Conclusions and policy implications Mobile apps can be used to reach large populations with messages that are individually-tailored and effective at changing car seat safety behaviors. The tailoring algorithms and messages developed in this trial could form the basis for using this technology in other settings and with other populations.