What is a Chest Clip in a Baby's Car Seat?

Often Overlooked, But Important

Baby in Car Seat
The chest clip, or harness retainer clip, is the gray plastic piece at the lower right. It's hard to tell since this child is wearing a thick coat under the harness, but the harness retainer clip appears to be positioned too low for this child, which could allow ejection from the seat in a crash. Michelle Gibson/E+/Getty Images

A chest clip is the plastic two-piece buckle found on the shoulder straps of a car seat harness. It's actually called a harness retainer clip, but chest clip is the more commonly used term. The purpose of the harness retainer clip is to keep the two harness webbing straps positioned correctly on the child's shoulders.

Do All Car Seats Have a Chest Clip?

A very small number of infant car seat models have a one-piece chest clip. The one-piece style is much less common than it was a decade ago, when it was found on almost every popular infant car seat model. In fact, seeing a one-piece chest clip nowadays is a somewhat reliable way to tell if a car seat is old and likely expired. However, you should always check the manufacturer's labels on the car seat, and the instruction manual, to make a final determination.

While some European car seats do not use a chest clip, nearly all American and Canadian car seats do have one. Use of the chest clip is integral to proper performance of the car seat in a crash. In the U.S. only one manufacturer, Kiddy, has a car seat model without a chest clip, and it's because they use a unique European style restraint system without shoulder harness straps. All other harnessed car seats, both rear-facing and forward-facing, will have a chest clip. If a chest clip is not present on the car seat, it likely means the seat has been disassembled and put back together wrong. Check the manufacturer's instructions for confirmation.

How Important Is The Harness Retainer Clip?

The harness retainer clip is a pre-crash positioning device, meaning it does its most important duty before a vehicle crash occurs. The clip, when used properly, keeps the car seat harness in the right place against the child's shoulders, so that crash forces are distributed over the strongest parts of the child's upper body.

If the clip is positioned too low, the child's shoulders could come out between the shoulder straps, and the increased movement increases the chance of injury. If the harness is loose and the clip is too low, the child could even be ejected from the car seat entirely. A chest clip that is positioned too high, up against the child's neck, could press against the soft tissue and cause injury in a crash. It's also not very comfortable to have a rigid clip against the neck!

Some parents report that, after a crash, they noticed that the harness retainer clip of their child's car seat was bent or broken. This does not mean the car seat did not do its job during a crash! As long as the chest clip keeps the shoulder portion of the harness in the right place until a crash occurs, it has performed adequately. Car seats, like air bags or motorcycle helmets, are a one-crash safety device. Some pieces of the car seat can break or warp as part of the process of deflecting and distributing severe crash forces in order to protect your child. A crash severe enough to break a chest clip most likely warrants a new car seat afterward.

The chest clip of your child's car seat should always be fastened and positioned at the child's armpit level unless the manufacturer's instructions tell you otherwise.

Heather Wootton Corley is a certified Child Passenger Safety Technician-Instructor.