Parents should be advised to carry children in rear-facing car seats until the age of four, according to a new study.

Many babies are switched to a forward-facing car seat at about eight months, with parents unaware of the potential safety implications.

Evidence suggests that a rear-facing seat is safer in the event of a crash and can help to avoid neck, chest and spinal injuries.

Dr Elizabeth Watson, a GP at the Sunny Meed Surgery in Woking, and Dr Michael Monteiro, a specialist registrar at the Royal Surrey County Hospital in Guildford, have analysed existing data on car seats.

They found rear-facing seats are more effective than forward-facing seats at protecting children under the age of four. In rear-facing seats, the head, neck and spine are kept more aligned, distributing the force of the crash more evenly across those areas.

In a front-facing seat in the event of a head-on collision, the relatively large head of a young child can add to the likelihood of severe injury.

Using the US National Highway Traffic Safety Administration’s vehicle crash database, the authors investigated incidents involving 870 children between 1998 and 2003 and found rear-facing seats were more effective than forward-facing seats in both head-on and side-on crashes.

They also looked at data from Sweden, where about three in four young children travel in rear-facing seats. The data suggested three out of the six children who died in front-facing seats between 1999 and 2006 could have survived if they had been travelling in rear-facing seats.

Publishing their findings in the British Medical Journal Online, the authors said many parents and healthcare providers are unaware it is safer to leave children in rear-facing seats for as long as possible or even that rear-facing seats for toddlers exist.

And they urged a change to the current labelling of European seats which they said may imply forward-facing seats are just as safe as rear-facing seats for children over 20lb (9kg).