How can I keep my baby from getting a flat head?
The most common cause of this flattening is positional, so it's a good idea to change the position of your baby's head while she sleeps. Having her sleep with you in a safe family-bed environment (no fluffy comforters or pillows, and no gaps between the bed and the wall) makes it easy to change her head position from time to time. If your baby sleeps in a crib, place her head at opposite ends of the crib on alternating nights to position her head differently. Also hang mobiles above the crib and place posters on the walls to engage her and get her to turn her head from one side to the other.
Babies who sleep on their backs have a reduced incidence of SIDS, so heed advice from the American Academy of Pediatrics and place your baby on her back to sleep until she is at least 6 months old.