-- Facing the rear: Children are five times safer facing the rear until they are two years old and should ride in that position unless they exceed the maximum rear-facing weight or height allowed by the seat maker. Rear-facing child seats provide the best protection for the head, neck and spinal cord.
Child seat technician and crash surivor Anne Hamilton says it's typical for babies in rear-facing seats to get fussy when they are 7 to 9 months old, but that they get through it and can adjust well to the position for many more months.
Facing the front: Children aged 2 or older (and those younger than 2 who have outgrown their convertible safety seats) should ride in forward-facing safety seats with harnesses until they reach the maximum weight or height allowed by the manufacturer. All models can be used up to 40 pounds, but many newer harness designs can be used until children weigh 50, 65, or more pounds. Front-facing harnesses spread force over wide areas of small bodies, reducing injury risk.
Make sure child seats are attached snugly. And don't forget to use the top tether strap to keep the child's head from flying forward in a crash, says Marc Cohen, who became a child seaat technician after his 2-year-old grandson died in a crash. He was in a child seat that was not properly installed.
In a booster: Children who have outgrown the weight or height limits of forward-facing safety seats should ride in belt-positioning booster seats until the vehicle lap and shoulder belts fit correctly. This is usually between ages 8 and 12. The lap belt should fit flat across a child's upper thighs and the shoulder belt should cross snugly over the middle of a child's shoulder. Booster seats keep belts on body parts that don't injure as easily as internal organs.
In a belt: A seat belt fits when a child's back and hips are against the vehicle seat back and their knees bend naturally over the front edge of the seat; the lap portion of the seat belt stays low and snug across the upper thighs; the shoulder portion stays snug across the mid-chest and shoulder; and this position can be maintained for the ride.
In the back seat: Children under 13 are 40% safer in the back seat, whether or not there are air bags. And never place a child in a rear-facing child seat near an active frontal air bag.
Source: Traffic Safety Projects; USA TODAY research