Most convertible car seats can be used from day one of a newborn’s life until she reaches the maximum weight or height requirement in the forward-facing position. In most convertible car seats, that’s around 65 pounds and 40 to 49 inches tall. This means your child will be able to ride in the same convertible car seat as a newborn, toddler and even preschooler.

Both infant car seats and convertible car seats have pros and cons to consider. 

Infant car seats are rear-facing only. They have a lower weight limit than convertible car seats, and can usually be used until your baby is 22 to 35 pounds and 26 to 35 inches, depending on the model. Infant car seats are smaller than convertible car seats, have carrying handles and can be easily clicked in and out of their base. This makes them more portable. “They typically come with a detachable carrier that can be easily installed and removed from the vehicle, often compatible with travel systems and strollers,” Dr. Chan says.

Convertible car seats can be both rear- and forward-facing. This means you can use them from the day you bring your newborn home from the hospital until she reaches the maximum weight or height requirement for the seat’s forward-facing position, which is usually sometime in the preschool years. As a result, a convertible car seat is a better long-term investment. “Convertible car seats offer longer-term value as it grows with the child,” says Dr. Chan. The downside is that convertible models are much less portable — they can’t be easily taken out of the car and clipped into a travel system stroller, for example.

An infant car seat might be right for you if:

• You want to be able to use your child’s car seat as part of a travel system
• Your child will be a passenger in a few different cars (yours, your partner’s, a grandparent’s, etc.) and you don’t want to buy a separate car seat for each

A convertible car seat might be right for you if:

• You want to invest in one car seat when your baby is a newborn and not replace it for many years
• You don’t mind not being able to easily take your child’s car seat in and out of the car or use it as a stroller attachment

Once your child has met the maximum weight or height requirements for the forward-facing position of her convertible car seat, you can transition her to a booster seat. According to the AAP, she should stay in the booster until the vehicle seat belt fits properly, which is when she is at least 4 foot 9 inches tall; most children will not get a good fit from car seat belts until they're 10 to 12 years old.