Allowing a baby sleep in a car seat could be deadly, experts have warned.

Researchers at Penn State Milton S. Hershey Medical Center examined the records for 47 infant deaths associated with sitting or carrying devices and have warned that babies should not be allowed to sleep in a car seat without being monitored.

If babies are allowed to sleep in car seats without being checked regularly,they are exposed to the risk of strangulation and suffocation.
The American Academy of Pediatrics recommends that infants sleep on their back on a firm mattress, without any lose bedding.
And Dr Batra and his team recommend seven key points for parents to remember when putting their children to sleep:

Do not leave children unsupervised

Never leave children in a car seat with unbuckled or partially buckled straps
Car seats should never be placed on a soft or unstable surface
Infants in bouncers, strollers, and swings may be able to manoeuvre into positions that could compromise their airway; straps on devices may not prevent infants getting into hazardous situations
Ensure that infants cannot twist their heads into soft bedding or slump forward in a seat; restraints should be used according to manufacturer's instructions
Slings are particularly hazardous because of their design and the ease with which an infant's airway can be collapsed. If used, a baby's face should be visible and 'kissable' at all times
Do not place more than one infant together in a swing meant for one infant
The study is published in the Journal of Pediatrics.