We all want our babies to be comfortable and happy during car rides, so it totally makes sense that some parents seek out aftermarket accessories to make car seats more cozy or more fun. Clip-on playthings, head cushions or soft strap covers can be tempting when you’re shopping in the baby section, but using them may actually defeat the purpose of your car seat.

Aftermarket, third-party accessories can void car seat warranties and, even worse, make babies less safe.

If it’s not specifically approved by your car seat’s manufacturer for use with your seat, you shouldn’t use it.

One mom, Hannah McKinney Pope, recently learned that lesson after her 2-month-old daughter was ejected from her car seat during a vehicle rollover. In a now-viral Facebook post warning other parents, McKinney Pope blames faux shearling seat belt covers, an aftermarket accessory she’d added to her daughter’s car seat, noting that the car seat straps and base worked as expected and stayed tight, but the third-part gear she’d added worked against the car seat in the crash.

“The sheep skin [sic] slid against her shirt and made her go flying out. Please please please people DO NOT put things on a car seat that did not come that way from the manufacturer,” McKinney Pope wrote on Facebook.

 

Third-party, aftermarket accessories are not recommended by car seat experts or manufacturers as they are not subject to the same government regulations as car seats.

Aftermarket harness strap covers, like those used by McKinney Pope, are specifically recommended against as they can prevent the straps from being tightened properly and prevent the chest clip from being positioned at chest level. If a long strap cover prevents the chest clip from being positioned properly, the risk of an ejection increases.

Head supports that were not designed for your particular cat seat, as well as seat covers, dangling toys and attachable mirrors are also not recommended.

Related: A parent’s guide to car seat safety: Tips, rules & product picks

Joe Colella, the Director of Child Passenger Safety for the Juvenile Products Manufacturers Association (JPMA), says car seats must be used according to the car seat and vehicle instructions in order to protect children from crash-related injuries.

“Only use accessories that are specifically recommended by your car seat manufacturer for use with your car seat. If inappropriate accessories are added, the safety and performance of a car seat may be compromised. If the car seat manufacturer does not allow the accessory, a child may be seriously injured and manufacturer warranties may be voided,” Colella tells Motherly.

He suggests parents check their car seat instruction manual, consult with manufacturer customer service, or review the car seat manufacturer website before adding any kind of child restraint accessory to a car seat.

Many car seats are sold with strap covers and other accessories that have been designed, tested and approved by the manufacturer for use with that particular seat. If you think you’d like to use car seat strap covers, or some other type of add-on, shop around for a seat that comes with that accessory specifically designed to work with that seat.

A lot of car seat manufacturers sell their own car seat accessories separately, so if you’ve already got a car seat, heading back to the manufacturer for accessories is the best bet, as long as the accessory has been tested and approved for that seat.

We all want our babies to be cozy and happy during car rides, but more than anything else, we want to keep them safe.

This story was originally published on April 18, 2018. It has been updated.