Practice Change Page

Advise use of rear facing child car seats for children under 4 years old

BMJ 2009; 338 doi: http://dx.doi.org/10.1136/bmj.b1994 (Published 11 June 2009) Cite this as: BMJ 2009;338:b1994
  1. Elizabeth A Watson, general practice retainer1,
  2. Michael J Monteiro, specialist registrar2
  1. 1Sunny Meed Surgery, Woking GU22 7EY
  2. 2Department of Oral and Maxillofacial Surgery, Royal Surrey County Hospital, Guildford GU2 7XX
  1. Correspondence to: E A Watson eliwat1{at}yahoo.co.uk
  • Accepted 30 March 2009

This article explores why it is safer for young children to travel in a rear facing seat until they are 4 years old

Key points

  • Many babies are switched from a rear facing car seat to a forward facing seat at 9 kg (8 months of age for a boy on the 50th centile)

  • Excessive stretching or even transection of the spinal cord can result if a child is involved in a head-on crash while in a forward facing car seat

  • Rear facing seats are safer than forward facing seats for children under 4 years old

  • Parents and guardians should be advised to keep young children in rear facing seats for as long as possible

The clinical problem

In many countries it is a legal requirement that children under a certain height or age (1 m 35 cm or 12 years, in the United Kingdom) use child restraints appropriate for their weight while travelling in a car. This significantly reduces morbidity and mortality.1 European car seats for babies and young children are classified as group 0+ (from birth to 13 kg, and all rear facing) and group 1 (9-18 kg, often forward facing but can also be rear facing). Currently, many babies are switched from a rear facing to forward facing seat at 9 kg (age 8 months for a boy on the 50th centile.2 3 Evidence is mounting, however, that it is safer for young children to travel in a rear facing seat until 4 years of age.2 3 4 5 6 7 8

The evidence for change

The relatively large head mass and differences in the anatomy of the cervical spine in young children5 can lead to excessive stretching or even transection of the spinal cord if a child is involved in a frontal (head-on) crash while in a forward facing car seat.4 5 6 The younger the child, the lower the crash force required to cause spinal injury.4 In rear facing car seats, the head, neck, and spine are kept fully aligned, and the crash forces are distributed over all of these body areas.3 6 7 8 Additionally, the back seats of a car are safer places for children than the front seats.9 However, most rear facing car seats can be used on the front seat of a car if there is no active airbag.

A retrospective cohort study involving 870 children aged under 2 years analysed the protection offered by rear facing compared with forward facing child restraints.3 It concluded that rear facing seats were more effective than forward facing seats in protecting children aged 0-23 months for all crash types (odds ratio 1.76, 95% confidence interval 1.40 to 2.20) (box).

Pivotal study supporting rear facing car seats for young children

Methods

A retrospective cohort study by Henary and colleagues used the US National Highway Traffic Safety Administration’s vehicle crash database for 1998-2003.3 The database is representative and allows crash data to be extrapolated to provide national estimates. Of the 870 children studied (all aged under 2 years), 352 were in rear facing car seats and 518 were in forward car facing seats. The study defined injury as an injury severity score of 9 or more, which is considered to represent moderate and severe injuries.

Results and conclusions

It concluded that rear facing seats were more effective than forward facing seats in protecting children aged 0-23 months for all crash types (odds ratio 1.76, 95% confidence interval 1.40 to 2.20). Effectiveness estimates compared with no restraint were 93% for rear facing seats and 78% for forward facing seats. These were calculated using estimates of the percentage reduction in rate of injury if all children changed from being unrestrained to being users of the particular car seat type. In side impacts, children were much more likely to be injured in forward facing seats (5.53; 3.74 to 8.18). When children aged 12-23 months were analysed separately, the findings remained: children in forward facing seats were much more likely to be injured (5.32; 3.43 to 8.24).

Questionnaires and real life observations have shown that 70-75% of Swedish children aged under 3 years travel in rear facing seats.10 Swedish crash data support the use of rear facing seats.2 7 From 1999 to 2006 four children aged under 4 years and restrained in rear facing seats were killed. The deaths were due to fire, drowning, or excessive intrusion and were unrelated to the type of car seat.2 During the same period six children aged under 4 years in forward facing booster seats were killed. Three of these crashes would have been potentially survivable if the children had been travelling in rear facing seats.2 There are no direct comparisons between rear facing and forward facing car seats as forward facing car seats are not commonly used in Sweden. Retrospective cohort analysis of all serious crashes reported to Volvo’s insurance company from 1976 to 1996 included 421 children in rear facing car seats and 950 in forward facing booster seats. The calculated injury reducing effect of rear facing and forward facing seats was 96% and 77% respectively.7

These real life data are supported by crash tests and numerical simulations, which support the use of rear facing seats until age 4. One study conducted 31 frontal crash tests with 12 month, 18 month, and 3 year old dummies restrained in both US and European rear facing and forward facing seats.8 All rear facing seats resulted in significantly lower injury measures for neck and chest compared with the forward facing seats; the European rear facing seats had the lowest injury risk.8 Another study conducted numerical simulations comparing a 3 year old dummy restrained in both forward facing and rear facing seats.11 It found that upper neck forces and neck injury criteria could be greatly reduced by using a seat that was rear facing. The conclusion encouraged manufacturers to develop rear facing seats suitable for children up to 4 years of age.

Barriers to change

Many parents and healthcare providers may be unaware that it is safer to leave children in rear facing seats for as long as possible or that rear facing seats for toddlers exist. Some parents may view the transition from rear facing to forward facing as progress. In many European countries it is more difficult, and can be up to twice as expensive, to obtain rear facing group 1 seats than forward facing group 1 seats. However, many rear facing seats are cheaper than the most expensive forward facing seats. In North America no rear facing seats are available that are suitable for children over 35 lb (15.9 kg).

Concerns that parents may have about using rear facing seats at an older age include motion sickness and the comfort and safety of the child’s legs. However, the leg is among the most frequently injured body regions for children in forward facing seats.6 Group 1 rear facing seats have modifications to provide leg room. No published evidence compares leg injuries or motion sickness in rear facing and forward facing seats.

How should we change our practice?

Healthcare professionals should advise that rear facing seats are safer than forward facing seats for children aged under 4 years.2 3 6 7 8 10 11 Always advise that parents and guardians should be shown how to install any child car seat in their own car by a trained fitter at the place of purchase or by a road safety officer. The health review at six to eight weeks and health visitor sessions are ideal opportunities for this counselling.

If parents do not have a rear facing group 1 seat, they should be advised to keep children in rear facing group 0+ seats up to the maximum weight or height limits for the seat. The American Academy of Pediatrics recommends that “for optimal protection, if a car safety seat accommodates children rear-facing to higher weight limits, the child should remain rear-facing until reaching the maximum weight for the car safety seat, as long as the top of the head is below the top of the seat back.”12

Manufacturers and retailers need to increase the availability of rear facing car seats for children over 9 kg. The current labelling for weight range used for European child car seats may imply that for children over 9 kg forward facing seats are as safe as rear facing seats. Manufacturers could cooperate with European government agencies to improve labelling.

Methods

We searched the Scopus database (which includes all Medline journals plus additional journals) for the terms “rear-facing car seat”, “forward-facing car seat”, “rear-facing child safety seat”, and “forward-facing child safety seat”. We also searched the reference lists of studies. We prioritised studies that directly compared rear facing and forward facing seats or that detailed advantages or disadvantages of either type of seat. We searched child car safety websites (childcarseats.org.uk, car-safety.org, rearfacing.co.uk, safekids.org) for further relevant published evidence.

Notes

Cite this as: BMJ 2009;338:b1994

Footnotes

  • Change Page aims to alert clinicians to the immediate need for a change in practice to make it consistent with current evidence. The change must be implementable and must offer therapeutic or diagnostic advantage for a reasonably common clinical problem. Compelling and robust evidence must underpin the proposal for change. We welcome any suggestions for future articles (changepage{at}bmj.com).

  • Contributors: EAW had the initial idea, performed the literature search, and wrote the initial draft. MJM did the literature search and reviewed the article. Both authors have seen and approved the manuscript The guarantor is EAW.

  • Competing interests: None declared.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

References