Winter brings cold weather and potentially slick roads, but families still need to travel every day. We bundle up our children to help them brave the elements, but a bulky coat and a car seat can be a dangerous combination.

There are ways to safely transport children in child car seats while still keeping them warm. Here are some tips for parents to follow from the experts at CR's Auto Test Center.

Puffy Coat Check

As a general rule, winter coats should not be worn underneath a car seat harness because that can leave the harness too loose to be effective in a crash. Here's a simple way to check whether your child's coat is too big to wear underneath a harness:

Step 1: Put the coat on your child, sit him or her in the car seat and fasten the harness. Tighten the harness until you can no longer pinch any of the webbing with your thumb and forefinger.

Step 2: Without loosening the harness at all, unhook it and remove your child from the car seat. Take the coat off, put your child back in the car seat, and buckle the harness straps, which should be adjusted just as they were when the child was wearing the coat.

If you can pinch the webbing between your thumb and forefinger now, then the coat is too bulky to be worn under the harness.

How to Bundle Up Safely

If you find that the coat can't be safely worn under the harness, here are a couple things you can do:

  • For smaller children, put a blanket over them to keep them warm.
  • Only use aftermarket covers, essentially fitted blankets, designed to give additional warmth that are approved by the car-seat manufacturer for your specific car seat. Such covers have been tested with the seat and won't compromise your child's safety.
  • For a bigger child, after securing him or her in the car seat, turn the coat around and put it on backward (with arms through the armholes), so the back of the coat serves as a blanket resting on top of the harness.

One of the most common problems with a child car seat is that the harness is left too loose, and wearing a big winter coat can be just one of the causes.

It's important that the harness is tight enough so that you can't pinch the webbing between your thumb and forefinger. Extra slack in the harness can let the child move to the point where he or she is beyond the protection of the car seat, perhaps even being ejected during a crash.