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Correspondence to Professor Timothy L McMurry, Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia, USA; [email protected]
Introduction
The recommendations for infants and young toddlers to ride rear-facing in their child restraint system (CRS) have been broadened in the USA in the last decade to extend beyond the traditional 1 year of age. The National Highway Traffic Safety Administration (NHTSA) currently recommends that all children less than 1 year old should be seated rear-facing and that those aged 1–3 years should ride rear-facing for as long as possible, until reaching the top height or weight limit allowed by the child restraint manufacturer.1 The American Academy of Pediatrics recommends that ‘All infants and toddlers should ride in a rear-facing seat until they are at least two years of age or, preferably, until they reach the highest weight or height allowed by their car seat manufacturer’.2 These recommendations reflect the biomechanical need to support a young child’s torso, neck and head, and distribute crash forces over the entire body. The weight of a child’s head and the anatomy of the developing spine, including incomplete vertebral ossification and increased ligamentous laxity, increase a young child’s risk for spinal cord injury and excessive head excursion during a crash. A rear-facing child restraint system (RFCRS) provides support to the head and spine that significantly reduces neck loading in crashes having a frontal component.3
The broadened recommendations were motivated by a series of research studies that evaluated the benefits of RFCRS. These included sled tests evaluating the biomechanical advantage of rear-facing3–6 and epidemiological data from the USA and Europe that documented the improved protection provided by RFCRS for these young occupants compared with other restraint conditions, including forward-facing child restraint systems (FFCRS), seat belts or no restraint at all. Swedish researchers and public health authorities have long been strong advocates of extended rear-facing. Children in that country remain rear-facing up to 4 years of age and transition directly from the RFCRS to a booster seat. Their policies cite Swedish data that quantify a reduction in the risk of Abbreviated Injury Scale (AIS) 2+ injuries of 90% relative to unrestrained children.7 8 Using US data, Hertz9 documented a reduction in fatal injury by 71%...