How Child Car Seats Work

Rear-facing Infant Seats and Convertible Seats

Graco SnugRide This rear-facing seat has a separate plastic base that can be left in your vehicle, while the seat serves as portable unit.
Graco SnugRide This rear-facing seat has a separate plastic base that can be left in your vehicle, while the seat serves as portable unit.
Photo courtesy

­Rear-facing infant seats are generally suitable for babies up to 22lbs (about 10 kilograms), roughly from birth to 12 months. Although they can be fitted in the front if absolutely necessary, it is much safer to install all child car seats in the back seat of the car. This is especially important if there is a passenger side air bag in the front seat. Were anything to cause the air bag to deploy, the force of the deployment would be enough to cause serious injury to a child in the front seat. In fact, according to the National Highway Traffic Safety Administration (NHTSA) all children age 12 and under should ride in the back seat.

The rear-facing design of these seats provides greater protection for the baby's head, neck and spine than forward-facing seats, and it really is best to keep your baby in a rear-facing seat for as long as possible. Of course, once the child has exceeded the maximum weight of the baby seat, it no longer offers adequate protection. The same is true if your child's head has become higher than the top of the seat, when it will no longer be properly cushioned against an impact. At this point, replacement with a seat specifically designed for toddlers is necessary.

Some infant seats come with additional features that may increase safety or simply make using them more convenient. Some models have detachable bases that attach to the car, to remain in place until the seat is no longer necessary. The actual safety seat simply snaps onto the base and locks in place, allowing you to use the seat as a baby carrier. This way your baby can be carried in and out of the car without having to re-install the entire seat each time. In some models, the base may be adjusted for comfort, or to give more room for growing babies.

If you're finding it difficult to locate a seat to fit your child's height and weight then shop around - some manufacturers offer convertible seats with higher weight and height limits. A convertible seat is bigger and heavier than an infant-only seat, and can be used longer and for larger children. Once your child reaches the appropriate weight or height, a convertible seat can be turned around and, by following the manufacturer's instructions, used as a forward-facing child seat.

Infant and convertible seats are fastened into the car using the vehicle's seatbelt and/or LATCH system (discussed later in this article), and the child is secured to the seat with one of the following harness styles:

  • The three-point harness has straps that cross over the shoulders and fasten to a buckle near the bottom of the seat.
  • The five-point harness has five straps: two at the shoulders, two at the hips and one at the crotch.
  • The overhead shield features a padded shield that swings down around the child, similar to the restraints often found on fairground rides.
  • A t-shield consists of a padded t-shaped or triangular shield attached to shoulder straps. Rather than swinging over the child, this shield is attached to the front of the unit.
Three-point harness system Three-point harness system
Three-point harness system
Photo courtesy NHTSA
Five-point harness system Five-point harness system
Five-point harness system
Photo courtesy Graco SnugRide
Overhead shield harness system Overhead shield harness system
Overhead shield harness system
Photo courtesy Graco Accel Overhead Convertible Car Seat

If you're thinking about purchasing a convertible seat rather than a dedicated rear-facing model, bear in mind that an overhead shield or t-shield may not be suitable for small children. In fact, the five-point harness is considered to be the best option because it is easily adjusted to perfectly fit your child.

Now, let's take a look at forward-facing child car seats.