I found this on the website babyzone.com. My daughter is 2, & I didn't trust myself to remember!! But now that I read it, I do remember that they say even if your child reaches 20-22 pounds prior to 1st birthday, they need to reamin rear-facing until they are 1 year old, something to do with muscle development, I think. Anyways, hope this helps!!
Infants
- From birth to one year AND 20 to 22 pounds, children should be in rear facing infant or convertible seats.
- Harness straps should be pulled up to shoulder level or just below.
- Do not put a child in a side passenger seat equipped with air bags.
Toddlers
- Children over 20 pounds and one year, but under 40 pounds can face forward in a convertible or forward-facing car seat.
- The harness straps should be at or above shoulder level.
- Never use pillows, books or towels to boost a child. They can shift in a moving car.
- Never allow a toddler to buckle himself in unless you check to be sure the seat is securely fastened.
Preschoolers
- Children between 40 and 80 pounds should be in a booster seat (belt-positioned), using both a lap and a shoulder belt.
- Be sure that the lap belt fits low and snugly to prevent injury to the abdomen in the event of an accident.
- Children should be in a booster seat until they are 80 pounds and 57 inches tall -- this can mean as old as 8 to 10 years! An adult lap belt used on a smaller child rides up on the abdomen while the shoulder belt can cut across the neck. During a crash, this can cause critical injuries