PLEASE read the manuals that come with your child(ren)'s car seat. I notice many parents are not tightening the straps enough (or at all) and don't have the chest strap high enough. Having the car seat does not guarantee safety, but using the car seat (properly) can.
Also, the AAP and NHTSA both recommend that children under 1 year AND under 20 pounds be rear facing for AT LEAST a year. A child should not be turned around before this time under any circumstances. I have heard a few pediatric nurses comment that it is easier to fix a broken leg than a broken neck. Auto accident injuries can be very dangerous for infants, toddlers and children. Please take the proper precautions when buckling your little ones in.