Car seats a danger to infants when used indoors

Parents are being urged to not leave babies asleep in infant car seats indoors after weeks-old babies were discovered blue, scrunched up and not breathing in their safety seats.

Reporting in Friday's British Medical Journal, researchers from New Zealand describe nine cases of babies -- all but one of them healthy, full-term babies -- who experienced low oxygen levels while in their car seats.

All but one case occurred when the babies had been left in standard, semi-reclining car seats for newborns on a floor or table.

In one case, a 10-week-old boy was found blue in his car seat in the kitchen. In another, a five-week-old was discovered "very blue" and scrunched up in her car seat on the floor. Both mothers revived their babies with mouth-to-nose resuscitation.

"Car safety seats are car safety seats. They should not be used as a household bed," says Dr. Alistair Gunn, an associate professor in the departments of physiology and pediatrics at the University of Auckland.

In just one case, a three-week-old turned purple while his mother was driving. She screeched to a stop on the side of the road, pulled the baby out, gave mouth-to-nose resuscitation and called an ambulance.

All the others were cases where the baby had been in the car but because they were "sleeping nicely" had been left on a floor to sleep quietly in the car seat, Gunn says.

What is it about bringing the babies out of the car that causes them harm? He has several theories.

It's known from studies of sudden infant death that babies are at much lower risk of SIDS if they sleep in a crib in their mother's bedroom.

"I think young parents and babies are very aware of each other," Gunn says. "Mothers are consciously or subconsciously always aware of what their baby's doing and how they are breathing, and I personally believe it works the other way around, that the baby is subconsciously aware that mum is there. In some way, that is making a difference."

In the car, "mum or daddy is right there in the seat next to them," whereas once they're inside the house, they're coming and going.

As well, cars jiggle and move. Babies fall asleep in the car, but they tend not to fall into a deep sleep.

All the babies in the study survived.

But later, when the scenes were reconstructed using the infants' own car seat, their heads bent forward with the jaw pressed down on the chest, narrowing the upper airway.

"You've seen how awkwardly babies slouch in car seats," Gunn said. "If they're in that much deeper a sleep, their neck muscles are going to relax more, their head is going to fall further forward.

"It's a small risk, but it's one we don't need to take."

Used properly, car safety seats reduce the risk of injury by 90 to 95 per cent for rear-facing systems and 60 per cent for forward facing seats, according to the U.K. Accident Prevention Trust.

But "even a semi-reclining seat is more upright than a newborn baby really wants to be," Gunn said.