It is absolutely safest to keep her rear facing as long as possible. My kids don't turn around until they max out the rear facing limit on the seat. For more information - the kid safe coilition says... www.usa.safekids.org
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Q. When can I turn my infant forward facing?
The American Academy of Pediatrics has recently revised their recommendations to say that children should ride in rear-facing child safety seats as long as possible. They also maintain that children should be a MINIMUM of 12 months old AND weigh at least 20 pounds before they face the front of the vehicle. Until that time, their bones and ligaments are not developed enough to withstand forward-facing crash forces. The rear-facing position reduces the risk of spinal cord injury in a frontal collision, since the safety seat's shell supports the neck and spreads crash forces across the entire back. Most infant-only seats have a limit of 20 or 22 pounds, but most current convertible safety seats have rear-facing limits of 30 pounds or more. These seats provide better protection for children, even beyond their first birthdays. "
UPDATE to address Kim's comment --
Q. My son's feet are touching the back of the vehicle seat. Should I turn him to face front now?
At one time, a few manufacturers were concerned about the potential for leg injuries. At this point, we are not aware of any documented injury cases resulting from that situation. We are, however, aware of many documented neck injury cases from turning children around too early. As a result, most manufacturers have softened the related warning in recent versions of their instructions.
Hope this helps!