With cold and snowy winter days upon us, child safety experts are reminding parents to take precaution before bundling their little one up and strapping them in a car seat.

"Children should never be placed in a car seat while wearing a snowsuit or puffy winter coat," said Alix McNulty, injury prevention coordinator and certified child passenger safety technician at Advocate Children's Hospital. "If a car accident were to occur, the coat's extra material might compress, which would make the car seat straps too loose."

McNulty explains that children can be at risk of being ejected from their seat if the strap is too loose or twisted. So, how can parents keep their child warm while keeping them safe in their car seat?

"Set your child's puffy jackets to the side and opt for dressing them in thin layers," said McNulty. "The American Academy of Pediatrics recommends parents start with closefitting layers on the bottom, like tights, leggings, and long-sleeved bodysuits, followed by a warmer layer of pants and a sweater. Winter accessories like hats, gloves and socks can be worn without interfering with the effectiveness of the harness straps."

In addition to heightened awareness of car seat safety during the winter months, McNulty also advises parents to be aware of the following common car seat mistakes and offers ways to fix the errors:

Mistake No. 1: Not reading the manual

Few parents take the time to read the instruction manual that comes with their child's car seat. The manual contains crucial installation instructions and height and weight requirements.

Can't find your manual? Check the manufacturer's website. Upon purchase, parents also should complete the seat's registration card so they can be contacted quickly in the event of a recall.

Mistake No. 2: Not researching the expiration date

Just like dated milk or cheese, car seats expire and are not safe to use past the expiration date. They typically expire six years from the date of manufacture -- not to be confused with the date of purchase.

Expiration dates are in place because safety standards and features change over the years and the seat's plastic casing wears down over time. The expiration date is often printed on the bottom of the seat.

Mistake No. 3: Turning the infant forward prematurely

According to the American Academy of Pediatrics, children cannot be turned forward until they are at least 2 years old, but it is ideal that they stay rear-facing as long as possible or until they reach the weight and height maximum of their seat.

Mistake No. 4: Not knowing the history of the car seat

Parents should never purchase or accept a used car seat if they do not know its history. Even a minor car accident can damage internal parts in the car seat, making it ineffective.

Car seats should never be bought at a garage sale or thrift store.

Parents who are still unsure if their child's car seat is correctly installed should make an appointment with a certified car seat technician.

Advocate Children's Hospital offers free car seat checks at both campuses in Oak Lawn and Park Ridge, as well as Advocate Sherman Hospital, Advocate Condell Medical Center and Advocate Illinois Masonic Medical Center.

• Children's health is a continuing series. This week's article is courtesy of Advocate Children's Hospital. For more information, visit www.advocate childrenshospital.com.