Fortunately, most premature babies have gained enough weight by the time that they are sent home from the NICU that they are able to sit in a regular car seat just fine. In fact, most NICUs make sure that their premature babies pass a 'car seat test' before they can go home.
This car seat test for premature babies typically involves having the baby sit in the car seat for a period of time while still in the NICU and making sure that he doesn't have any problems with his breathing or heart rate.
