A first time mother or parent will probably be puzzled with the types of baby car seat. At least, the very basic and bigger picture is that a growing child will need a different seat.
Most new baby car seats in the U.S. market meet the stringent crash-and-fire safety standards. However, be mindful that second-hand baby car seats may not. This is because policies and standards could have changed and older models might have gone obsolete. Worst still, used baby car seats may have been broken.
Infant-only baby car seat
Generally designed for infants from birth till about 2 years old. Rear-facing seats for obvious reason where a young baby neck is not strong yet to support itself on any crash impact. Infant car seats usually come with weight and height limit. Once the baby has outgrown the maximum limits (usually 20-35 pounds or around 10-15kg), you should change to Convertible car seat.
Convertible baby car seat
A newborn can also use a convertible baby car seat up to around 2 years old. It is usually large and bulky which gives the feeling of safety. However, the disadvantage is you cannot use it as an infant carrier because it is not portable. It does not have a base and cannot be easily moved from one car to another. The plus side of it of course, it is more value for money. A baby can use it since birth until the weight and height limit is reached.
Nonetheless, the seat can and should be placed rear-facing for newborns until at least 2 years old. Thereafter, parent can position it to forward-facing. That is when a parent is sure and comforted that the child neck is strong enough to support the head. Most seats are designed to hold a baby up to 40 pounds (18kg) rear-facing and 70 pounds (32kg) forward-facing.
Booster baby car seat
When the baby is at least 4years old or minimum 40 pounds (18kg), you use a booster baby car seat. It is forward-facing, and usually comes with its own buckle or harness. It can also use the car existing seat belt. The height of your child determines which model is most comfortable. It is recommended to try out the baby car seat before buying. This type of baby car seat can sit a child up to 70 pounds (31kg)