Don't Let Sleeping Babies Lie -- in Car Seats

Car seats pose a potentially deadly threat to an infant's airways, study says


Dec. 8, 2006 — -- Texas father Mikey Terry realized his mistake when he found the lifeless body of his infant daughter, Mika, in the back seat of his truck.

Mika was 6 months and 9 days old when she died of hyperthermia after being tragically forgotten, in a rush of everyday distractions, on a hot June day in 2005.

Such stories -- all too common -- remind parents that a child's life can be ripped away in an instant should that child be left unattended in a car that is too hot or too cold. But few parents know that it isn't only the weather that poses a life-threatening risk, but also the car seat itself.

Newborn babies should not sleep in car seats and be left alone, according to a new study in the British Medical Journal. The consequences could be fatal.

The study looked at 43 infants in New Zealand who -- between July 1999 and December 2000 -- were referred to a hospital service that studies infants at high-risk for sudden infant death syndrome (SIDS).

Of those infants, nine had suffered some sort of apparent life-threatening event (ALTE) while in a car seat.

Four of the babies, when found, were described as "limp and nonresponsive," according to the study. All were found either "blue" or "not breathing."

The researchers then reconstructed the scene -- as if it were a crime scene -- and figured out that all nine of the babies had been sitting with their heads flexed forward and their jaws pressed against their chests. This position -- or, this head flexion -- narrowed the airways, making every breath a challenge.

Because "the infants [in the study] were very young [and their] head control is not well developed," the authors of the study said this head position is a potentially fatal one. Sleep poses an additional risk, because the throat muscles relax and make it hard to keep one's airway open.

Half of the infants were children of smokers -- and secondhand smoke is known to weaken a baby's drive to breathe. All of these factors help explain why a car seat is so potentially dangerous.

This is not to say that parents should not use car seats. More children are killed as passengers in car crashes, according to the American Academy Pediatrics (AAP), than by any other type of injury. And we know that car seats can reduce injury by up to 95 percent when used correctly, said Michael Hayes, the author of a letter accompanying the study.

Though this is the first study looking at infant position in car seats and death risk, the AAP has been recommending that "infants should ride at a 45 degree angle to prevent slumping and airway obstruction," according to a 2002 policy statement.

Doctors recommend that infant car seats should be modified "so that head flexion is unlikely," which could decrease the "risk of apparent life threatening events," said study author Dr. Shirley Tonkin, a general practitioner associated with the New Zealand Cot Death Association.

In the meantime, until the design of car seats changes, parents should be watchful of infants sleeping in car seats.

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