An infant car seat is designed for infants. This is usually from birth until your baby is at least 2 years old and reaches the weight limit for the seat. when he or she will likely need a bigger seat.
An infant car seat can last you six to 24 months, depending on the growth rate of your baby and the size of the car seat. Some babies outgrow the infant car seat faster than others. Once your child reaches the maximum weight OR height limit for the seat, it's time to switch to another type of car seat designed for older babies and toddlers.
Convertible Car Seat
Convertible car seats are used from birth until your child outgrows a car seat. This means that you can get more use out of your investment. They can be used in forward-facing or in rear-facing positions, depending on the weight of your child. Rear-facing is used for infants up to 3 years, and you can start putting your child in a forward-facing position once he or she is 3 years old.