Child Restraint Use and Effectiveness
Child restraint systems are highly effective safety devices that protect children against the leading cause of injury and death for those ages 5–18 years. There are four main sequential steps in child restraint best practice: rear-facing harnessed restraint, forward-facing harnessed restraint, booster seat with a lap-and-shoulder belt restraint, and seat belts. Matching the appropriate restraint mode with the child depends on their physical size and maturity level.
Relative to no restraint, rear-facing child restraints are 71% effective and forward-facing child restraints are 54% effective in reducing the likelihood of death and serious injury (Kahane 1986). Forward-facing child restraints reduce odds of an injury by 78–82% compared with lap and shoulder belts (Zaloshnja et al. 2007, Arbogast et al. 2004). Benedetti et al. (2019) report that for children under 2, use of rear-facing restraints reduces injury risk by 55% compared to suboptimal restraint, while for children aged 2-4, use of forward-facing restraints reduces injury risk by 41% compared to suboptimal restraint.
Children aged 2–6 using child restraints without gross misuse had a 28% lower risk of death than children using only seatbelts (Elliott et al. 2006a). Use of a booster seat reduces risk of fatal injury for children aged 4–8 years by 55–67% relative to the risk to unrestrained children and adults, while children aged 5–14 using seatbelts have a 52% reduction in fatal injury risk relative to unrestrained occupants’ risk (Morgan 1999). While proper booster seat use has only a marginal effect on reducing risk of fatal injury compared with the risk of using a seatbelt alone, children aged 4–8 using booster seats have a 55% lower risk of serious injury compared with those using seatbelts alone (Arbogast et al. 2009); more recent analysis indicates that children aged 5-10 using boosters have a 30% lower risk of injury compared to using seatbelts alone (Benedetti et al. 2019). In comparison, seatbelts are 37–48% effective at preventing fatal injuries in adults while seatbelts plus frontal impact airbags are 44–54% effective at preventing fatal injuries (Morgan 1999). While child restraints are the most protective restraints available, there can still be catastrophic crashes, particularly those involving severe intrusion into the passenger compartment of the vehicle, where child restraints are not effective and children can sustain severe or fatal injuries.
Tremendous strides have been made to increase child restraint use nationwide, primarily through the enactment of state child passenger safety laws and educational campaigns aimed at parents and caregivers (Bae et al. 2014, Klinich et al. 2016). Since 2000, 49 of 50 states have improved their child restraint laws either by extending the applicable child ages, making nonuse a primary enforcement infraction, or adding other best practice elements to the law. As a result, the number of children dying in motor-vehicle crashes decreased by 53% between 2000 and 2018 (FARS 2018, Sauber-Schatz et al. 2015, Sauber-Schatz et al. 2014). However, unrestrained children ages 0–15 years still account for approximately 20% of children killed each year in motor vehicle crashes (FARS 2018), indicating that additional gains in safety can be achieved by minimizing nonuse of child restraints further.
Misuse of child restraints remains common, with estimates of misuse ranging from 63–90%. (Hafner et al. 2017, Bachman et al. 2016, Decina and Lococo 2007, Decina and Lococo 2005, Dukehart et al. 2007) Some errors may have minimal effect on safety, particularly in less severe crashes. When performing dynamic testing using different types of misuse, Manary et al. (2019) found that loose installation, loose harness, and loose/missing tether had the greatest effect on forward-facing child restraint injury measures, while only misrouted belt path had a significant effect on rear-facing injury measures. However, multiple “small” errors may combine to cause as much of a decrement in performance as a single major error, and become more critical as the severity of the crash increases (Tai et al. 2011, Lesire et al. 2007, Weber and Melvin 1983). The effectiveness of child restraints is estimated from their “as used” state, which includes misuse conditions, and thus would be expected to increase if misuse were reduced.