Manufucturers currently advise that babies are not left in car seats for longer than two hours at a time as it could do damage to their developing bodies.
However, scientists are now suggesting that the advice may need to be revised as there could be a risk of suffocation to newborn babies travelling in car seats for more than 30 minutes.
It comes after findings from a pilot study into the effect on 40 newborns of a vibrating car seat, which revealed an increase in the babies' heart and breathing rates when travelling in a rear-facing car seat for half-an-hour. They also found that in some cases, babies' blood oxygen levels fell.
Led by Professor Peter Fleming - a paedtrician at Bristol University, and funded by the Lullaby Trust, researchers used a vehicle motion simulator to mimic the vibration felt by babies in a rear-facing seat in a car travelling at 30mph. The car seat was fixed at a 40 degree angle.
They measured the babies' breathing, heart rates and oxgyen levels while in the simulator, which they compared to a 'baseline' measurement - taken when they were asleep in a cot.
Their findings showed a 'striking' increase in the babies' oxygen levels, as well as an increase in their heart and breathing rates, when seated in an upright position in a car seat.
Prof Fleming said the findings could lead to a revision of current recommendations on the length of time a baby should be in a car seat.
He also said that the study supports the American Academy of Pediatrics (AAP) guideline that car seats should not be used as a routine infant sleep environment.
The Lullaby Trust, which funds research on infant deaths, is now calling on all baby car seat manufacturers to work together to develop and agree on consistent messages for parents when using car seats, especially for pre-term and young babies.
Speaking at its Infant Car Seat Research Seminar last week, Francine Bates, chief executive of The Lullaby Trust, said, 'We believe that parents should be given informed and evidence based advice when they purchase car seats. There is a tendency to focus on how best to fit a car seat and strap a baby in, but information on the potential health risks associated with driving long distances is not usually offered.
‘We advise parents that they should avoid travelling in cars with pre-term and very young babies for long periods of time. Ideally, a second adult should travel in the back of the car with the baby and a mirror should be used so the driver can keep an eye on the baby at all times. If a baby changes its position and slumps forward, then parents should immediately stop and take the baby out of the car seat.'
Ms Bates added, ‘This research was a pilot study and we need to find out a lot more about the effects of vibration on a baby, particularly over periods of distance and also at different ages. I hope that the infant car seat industry will give some consideration to helping us fund this work next year.'
The Lullaby Trust has asked researchers to submit a proposal for a further study monitoring the impact of vibrations on babies in cars on 'normal' journeys.
- The study - 'Is the infant car seat challenge useful? A pilot study in a simulated moving vehicle', is published in the Archive of Childhood Disease.