Right height Adjust the shoulder straps so they start at […]
Adjust the shoulder straps so they start at or below baby’s shoulder height. (This is the preferred position for rear-facing car seats.)
Position the chest clip at armpit level. It should be high enough to keep the shoulder straps in place but shouldn’t rest against baby’s chin.
Pull the shoulder straps snug, so there’s no extra slack to pinch. If you can fit two stacked fingers between a strap and your baby, it’s too loose.
Remove bulky jackets and sweaters, which can compromise a car seat’s effectiveness. If you’re concerned about baby’s warmth, tuck a blanket around him—and over the harness—after he’s strapped in.