A team of experts led by scientists from Bristol University found that sitting in a child seat can block a baby’s airways by causing them to slump forward.
This can lead to a reduction in the amount of oxygen in a baby’s blood supply and can even prove fatal in very rare circumstances, the researchers claim.
READ MORE: 10 top tips for child car seat safety
In the study, a group of 40 babies including 21 premature infants was examined during a 30-minute simulated car journey.
Heart and lung function were tested as the babies sat in an upright position of around 40 degrees.
The results showed that at the end of the simulated car journey, the children’s oxygen levels had dropped “significantly”, researchers said.
At the same time, the babies’ heart rate had increased and a portion of the test group was seen to flop forward.
As a result of the study, experts are advising parents to take extra care when travelling with infants.
They stress that mums and dads should continue to use properly secured child seats as required by law.
But the scientists add that parents should try to sit next their children in the back seat to ensure the baby continues to breathe properly.
IN OTHER NEWS: Young drivers admit to being unsafe behind the wheel
Dr Peter Fleming, of Bristol University, said: “No human is strong enough to hold on to a baby in a crash. The law says they must be in a car seat, that’s for a very good reason.”
One reason for the findings is thought to be babies’ lack of muscle tone.
This means they do not have the strength to support their head when travelling in a car seat.
As many car seats are designed to support children weighing up to 22 pounds, it is also thought that many models may be too big for some premature babies.
Hospitals currently require premature babies to pass a car seat challenge to make sure they will not have problems breathing when in the car.
The study was financed by the Lullaby Trust, a charity dedicated to preventing sudden infant deaths.
It was carried out at the Great Western Hospitals NHS Foundation Trust, with backing from Southampton and Bristol Universities.