Frigid temperatures mean extra layers, and when it comes to little ones that usually means bundling them up from head to toe. But could the extra layers be putting them in harm’s way, especially when it comes to car seats? At least one expert says yes.

“As a rule of thumb jackets, winter coats or snowsuits should not be worn while riding in a car seat,” Laura Flinn, an assistant professor in Bradley University’s online nursing program, told Fox News. “By having extra bulky clothing on the child, it prevents the harness from securing the child in place during potential accidents.”

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Flinn, who is currently researching children’s car seat safety, said the impact of an accident can cause the layers of clothing to flatten, which allows slack in the harness and puts the child at a higher risk of injury.

“You should always remove the jacket or extra clothing prior to securing the child in the car seat harness,” she said. “It is important to check the straps to make sure there is no extra slack after you buckle them in. The chest clip should be over the sternum securely.”

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While there is no federal law prohibiting a parent from putting their child in the car seat with a jacket on, Flinn said her advice follows the recommendations provided by the American Academy of Pediatrics.

Her guidance to parents and caretakers changes, however, when it comes to winter accessories such as hats and gloves.

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“As long as the accessories do not get in the way of the harness or straps, they are fine to wear,” she said.

The same is true for blankets, which can be used to help keep the child warm after they have been safely secured in the car seat. Or, Flinn said, you can have the child wear their jacket backward over their arms and chest after they have been buckled in.

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“Winter months are known to have [a] higher risk of car accidents due to inclement weather,” she said. “If the children are not secured properly this puts them at high risk of injury or death.”