It’s a nightmare no parent ever wants to imagine—their sleeping child forgotten in the back seat of the car on a hot summer day.

A study co-authored by pediatricians at St. Michael's Hospital Department of Pediatrics and SickKids is highlighting how quickly children can die when trapped in hot cars, and how easy it is for parents and caregivers to forget them by accident.

The study, published in Paediatrics & Child Health, is the first to look at the incidences and causes of pediatric hot car deaths specifically in Canada.

Using data from all provincial and territorial coroner’s offices as well as media articles, the team determined there has been an average of one child death per year due to vehicular hyperthermia in Canada since 2013.

Hyperthermia is a condition that occurs when the body can no longer release enough of its heat to maintain a normal temperature. Children are more susceptible to hyperthermia because their body’s heat-regulation system is less efficient than an adult’s.

“The literature shows that even on what we might consider a cooler day in the summer— like 21 C or 22 C—the temperature inside of a car can rise to 40 C within an hour,” says pediatrician Dr. Joelene Huber, who led the study.

Most incidences in both the United States and Canada occur as a result of a parent or caregiver forgetting that a child was in the car, sometimes referred to as “forgotten baby syndrome.” Dr. Huber says studies have noted the rise in these incidences after the 1990s when children’s car seats began being placed in the back seat of vehicles with the introduction of front seat airbags.

The team, which also includes Drs. Mike Sgro, Ripudaman Minhas, and Elizabeth Young, researchers in the Li Ka Shing Knowledge Institute of St. Michael’s, noted stress and a change in routine are often the main reasons parents or caregivers say they forgot their child in the car.

“When you drive to and from work everyday you don’t have to use all of your cognition and energy to concentrate on how to get home if you always take the same route—our brain is designed to go into a kind of autopilot,” says Dr. Huber.

“But when you change your routine—let’s say you don’t usually have the baby in the car, but today you have to drop the baby off at daycare—it’s easy for your brain to slip into that autopilot and you can forget.”

The study outlines several recommendations for parents and caregivers to help prevent this tragic accident:

• Never leave a child unattended in a motor vehicle—even for a minute
• Ensure children can’t access parked vehicles—vehicles parked in the garage or on the driveway should always be locked and the keys kept out of reach of children
• Create reminders—Put something you will need when you leave the vehicle in the back seat (ie, cellphone or wallet). “You can also leave a stuffed animal on the car seat, and move it to the front seat whenever you place a child in the car seat,” says Dr. Huber. Ask your child-care provider to call if your child doesn’t show up and to keep calling until someone answers
• Make it a habit—Always check the back seat when you leave your car. Regularly engage with your child while driving by talking or singing, even if they’re sleeping, to avoid slipping into autopilot.

“I think the most important thing to stress is that when you hear about these kinds of cases they’re so devastating and some people say, ‘That could never happen to me,’ ” says Dr. Huber. “But it’s better for parents and caregivers to be in the mindset of ‘this could happen to me’ and make sure you’re vigilant.”

The team hopes to continue its work in this area by studying whether parents become more aware of the risks of leaving children unattended in a car if a discussion is incorporated into the typical car seat safety coaching that occurs prior to hospital discharge with newborns.

—Danielle Pereira