flat heads are cause when a baby spends too much time on a certain part of his/her head. if they have a flat spot on the back, roll them over on their tummy more. if they have it on the side, turn their head to the opposite side when they sleep. it'll eventually regain roundness but if in a few weeks you don't notice any change, talk to the baby's pediatrician about it. they can give you a shaping helmet if it's a problem or seems to be causing problems.