Automotive Safety Program

Types of Child Safety Seats

Infant only child safety seats
Infant only child safety seats are designed for newborns and infants who weigh up to 20-22 pounds and are approximately 26 inches in length (until their head is within an inch of the top of the child safety seat). These child safety seats are designed to be used rear facing only.

According to the American Academy of Pediatrics (AAP), infants should ride rear facing until they are at least one year old and at least 20 pounds. If an infant outgrows an infant only seat

Four month old infant in
Infant Only seat with detachable base.

before he or she is a year old, the infant should be moved into a convertible seat that is designed to be used rear facing to 30 – 35 pounds. Since the rear-facing position helps to protect a child’s neck from injury in a forward impact, a child should ride rear-facing until they have reached the rear facing limits on height or weight, as specified by the manufacturer. (Click here to learn more about rear facing.)

Many infant seats come with detachable bases. These types of seats can be installed in the vehicle with or without the base. The seat belt path will vary depending on whether or not the base is used.

Convertible child safety seats
Convertible child safety seats are designed to be used both rear facing and forward facing. They are “converted” from the rear facing to the forward facing position by making specific changes to the seat, which are described in the manufacturer’s instructions.

There are three types of harnesses in convertible child safety seats, 5 point, t-shield and tray shield harnesses.

Five point harnesses contact the body in five places, both shoulders, both hips and between the legs. It can be adjusted to fit a variety of infants and toddlers snugly and correctly.

T-shield and tray shield harnesses secure the two shoulder harnesses

to a “T” shaped shield or a padded tray and buckle between the legs. These types of harness are not appropriate for small babies because their head and upper body can hit the shield during a crash. The AAP does not recommend them for small infants because the harnesses do not make good contact with the baby’s upper body and the infant’s head/face may contact the shield during a crash or abrupt maneuver.	Do not select a tray or t-shield harness for a small infant. Image provided by NHTSA
In the rear-facing position, the convertible seat is designed to be used by children who weigh up to 20-35 pounds (check the instructions). Most newer convertible seats have upper rear-facing weight limits of 30-35 pounds. Riding rear facing until they reach the manufacturers’ weight and height limits allows children to receive maximum protection in a crash, well beyond a year.	Four month old infant rear facing in convertible seat.
In the forward-facing position, the convertible seat is designed to be used for children who weigh up to 40 pounds and are 40 inches tall (until the mid-point of their heads are above the top of the child safety seat or their shoulders are above the top harness slots).	Three year old in forward facing convertible seat.
Forward-facing only seats There are currently two types of forward-facing only seats. The first type is referred to as a harness only seat. These seats must be used forward-facing and use a harness to restraint the child. The upper weight limits vary, but some will accommodate a child who weighs more than 40 pounds. These seats are extremely helpful for children who are over 40 pounds and must ride in a lap only vehicle belt since belt positioning boosters (BPB) require lap and shoulder belts.	Seven year old in harness only seat with maximum weight of 80 pounds.
The second type is referred to as a combination seat. These seats must be used forward-facing. They use a harness to restrain a child until 40 pounds. At 40 pounds the harness is removed and the seat is used as a belt positioning booster. As a BPB, the seat is designed to be used to 60-80 pounds (check manufacturer’s instructions). Many newer BPBs can be used to the higher weight limits.	Four year old in combination seat
Booster seat These seats are subdivided into two types, the belt positioning boosters and shield boosters. Belt positioning boosters are recommended for children who have outgrown their forward-facing child safety seats with harnesses, but are too small to wear an adult seat belt. This is usually when the child reaches approximately 40 pounds or 40 inches. In general, belt positioning boosters are designed for children who weigh approximately 40-80 pounds. Belt positioning boosters assist with proper positioning of the adult lap/shoulder seat belt system. A child won’t be ready to graduate to the seat belt alone until he can sit with his back against the vehicle seat without slouching, and his knees comfortably hang over the edge of the vehicle seat, preferably with his feet touching the floor and the shoulder belt does not cross his throat. Also, the lap portion of the belt must fit snugly over the upper thighs and low on the hip bone.	Child in high back belt positioning booster seat.

Children generally fit appropriately in adult seat belts when they are about 4’9”, about 80 pounds and between 8-12 years old.

There are two styles of belt-positioning boosters:

1. A backless booster is a small base that allows the child’s back to make direct contact with the back of the vehicle seat. It does not contain a head support system. Therefore to use a backless booster, the vehicle seat must provide head support that is above the child’s ears.

Child in backless booster
Image provided by NHTSA

2. A highback booster has a tall back that helps to protect a child’s head and neck in vehicles that have low seat backs.

Child in highback booster
Image provided by NHTSA

Shield boosters have a small base that a child sits on and a shield that comes over a child’s lap. Current models are designed to be used with the shield from 30-40 pounds and without the shield as a belt positioning booster from 40 to 60-80 pounds. Shield boosters do not provide as much upper body protection in certain types of collisions as child safety seats with full harnesses. The American Academy of Pediatrics (AAP) recommends that children use a seat with a full internal harness until they reach the manufacturer’s recommendations for the upper size limits.