Parents beware. Babies should not be allowed to sleep in car seats according to a study published today by researchers from the University of Auckland.

While 78 infants are sleeping in car safety seats, researchers studied their breathing patterns. The car safety seats used in the study had foam plastic inserts. Other infants were placed in car seats with no plastic insert.

The results of the study show that infants sleeping with foam plastic inserts in their car seats have less breathing problems.

University of Auckland's Department of Physiology Dr. Christine McIntosh, said the new study highlights the importance of not letting parents use car seats for sleeping infants. She said that despite reduced breathing problems of babies sleeping in car seats with plastic inserts, young babies should not be left unattended on any seat device.

McIntosh said the use of car seats for infants should only be limited to a certain minimum time during travel. The findings of the Auckland researchers warned parents against car seat use in their report published today in the U.S. Journal Pediatrics.

McIntosh said that in a baby restrained to car seats in the first months of life often have brief periods of low oxygen saturation. There are occasional incidents of sudden unexpected deaths in infants (SUDI) happening in capsules or car safety seats.

University of Auckland researchers performed a randomised controlled study and discovered the use of foam plastic inserts help reduce the number of instances wherein infants stop breathing because of airway blocks and drop in oxygen levels.

According to the study, infants' heads slump forward when they fall asleep in their car safety seats. The researchers wanted to find out whether a foam plastic insert that supports the head of the infant upright during sleep can improve breathing patterns.

Researchers acknowledge that reducing the periods of low oxygen levels is important. McIntosh said the plastic insert can help make babies more secure in car seats.

The foam plastic inserts used in the car seats are sold commercially and specially designed to let infants sleep in a neutral position while sleeping.