Young babies have to be seated in infant car seats rear facing until they reach the height and weight limits mentioned on the manufacturer’s label. Do not be in a hurry to shift him from an infant car seat as it mainly relates to safety of your child. Keep him seated in rear facing as long as possible. If you face a front end collision, the rear facing seating will move your child’s head, neck and back evenly into the seat and not away from it. All infant car seats are manufactured for specific weight, height and age and meet or exceed the federal safety standards. For example, you can check the comparison on maxi cosi pria 70 vs 85 models and their individual effective performance.
The child has to be seated in rear facing car seats until they are 2 years of age. When your child grows you will have to shift from smaller rear facing car seat to a bigger rear facing convertible car seat that can accommodate a larger child. After the child reaches the limits of rear facing car seats he can be shifted to forward facing turning the convertible car seat to forward facing. You can also seat him in a forward facing only car seat that comes with 5 point harness and top tether. The child has to be seated in forward facing till he reaches the limits specified for forward racing before he moves to booster seats.
Once your child reaches the height and weight limits of the forward facing car seat, he can be shifted to belt positioning booster seat with shoulder and lap belt. Many studies have shown that when the rear facing car seats are thoroughly installed and given a proper fit they are capable of protecting your child from crash forces till up to 4 years of age.
When you feel that your child has overgrown his car seat, you can pass it on to someone. But ensure that the labels and original parts are intact and the seat has not suffered crashes so far.