Researchers in New Zealand recently tested a car safety seat insert designed to reduce the risk of young babies suffocating. While it showed some benefit, the researchers caution that it is still important for parents never to leave young infants asleep in their car seat.

Professor Alistair Gunn and colleagues from the Department of Physiology at the University of Auckland wrote a paper published online in Pediatrics this week. They found that while the foam plastic insert reduced the number of times young babies stopped breathing, it did not reduce the overall rate of low-oxygen episodes.

In 2006, Gunn’s team reported in a BMJ paper that preterm infants and full-term infants with certain health conditions are at risk of temporary suspension in breathing (apnea) while they are restrained in semi-reclining car safety seats. They also mentioned that studies show even some full-term infants can experience periods of low oxygen saturation.

While infant car safety seats are essential for protecting young babies from injury and death in traffic accidents, they should not be left unattended to sleep in them, they said.

Now in this latest paper, the team builds on their earlier research to investigate the effectiveness of an added safety insert, which is already available commercially, as lead author Dr. Christine McIntosh explains in a statement:

Babies’ heads usually slump forward when they fall asleep in their seats. We wanted to find out whether an insert that allows the infant head to rest upright in sleep could improve safety by reducing periods of low oxygen.”

For their randomized controlled trial, the team monitored body functions of 78 babies who were, on average, 8-days-old as they slept in car seats with the insert (39 infants) and without it (39 infants). The body functions measured included breathing and blood oxygen levels (hemoglobin oxygen saturation).

The researchers found that compared to the babies who did not have the insert, the babies who did experienced fewer episodes where they stopped breathing due to airway obstruction, accompanied by a reduced fall in oxygen levels during these episodes. However, the insert did not significantly reduce the overall rate of moderate low oxygen events.

The results showed that the car seat insert was associated with a significant reduction in three measures: the rate of obstructive apnea, the severity of oxygen desaturation events, and time when oxygen saturation fell below 85%.

“Both groups showed a small fall in mean hemoglobin oxygen saturation (SpO2) over the first hour of sleep,” write the authors, adding that there “was no difference between insert and no insert in the rate of moderate desaturations.”

They defined moderate desaturations as a fall in SpO2 of 4% or more, lasting for 10 seconds or more.

McIntosh says:

“Even reducing severity of the fall in oxygen levels is important and is a good indicator that the insert did help make babies safer.”

But she adds that the findings also highlight “the importance of not using cars seats as a place of sleep for infants.”

“Sudden unexpected deaths in infants (SUDI) can occasionally occur in car seats/capsules,” says McIntosh.

Other researchers have also urged that car safety seats for very young babies should be used only for protection during travel, and not as replacement for cribs.

Written by Catharine Paddock PhD