Missouri law requires kids to be in rear-facing car seats at least until the age of one. But the American Academy of Pediatrics recommends children stay rear-facing until age two. "Because pediatric patients, their neck muscles are not strong enough to withstand forces on an impact when they're forward facing until they're at least two-years-old," Lana Martin, a trauma nurse clinician at CoxHealth in Springfield, said. Under Missouri law, kids less than four-years-old or less than 40 pounds must be in an appropriate child safety seat. Children four to seven who weigh at least 40 pounds must be in an appropriate child safety seat or booster until they are 80 pounds or 4'9." Martin says seatbelts don't fit right until a child reaches that height. Every car seat is a little different on its recommended maximum weight. Martin says a good rule of thumb to follow is to move a child to a new car seat once their shoulders exceed the top of the car seat.