Car seats can restrict babys breathing  

First it was a danger of leaving a child strapped in on a hot day. Now, a new zealand study warns that children left to sleep in car seats are at risk of oxygen deprivation, even if parents bring them indoors. The study investigated nine publicized life-threatening emergencies involving children left in the car seats. Based on careful reconstruction of each case, researchers concluded that infants who fall asleep in the car seats are at an increased risk when their heads slouch forward, restricting the airways. The study's author recommended redesigning car seats to reduce the risk of infants falling asleep in the forward-head posture.

The key ingredients in all nine cases in the sample: The infants were left unattended for extended periods of time. When using the car seat, keep a close eye on the child, checking for changes, in their sleeping posture frequently.