There's some controversy over whether kids should be allowed to sit with their rear end touching the floor and their legs spread out at a 45-degree angle to form a "W." Some pediatric orthopedists say it can't hurt the hip at all, that it's more comfortable for kids who do it because of the way their legs fit into their hips. Others think that it stresses the hip joint and can cause damage. So what's a parent to do? If your child can just as easily sit cross-legged as in a W, I'd encourage him to sit that way. If he seems uncomfortable in that position, or goes into a W-sit as soon as your back is turned, leave him be. Mention it to your pediatrician at his next checkup, however, so she can do a thorough examination of your child's legs.
Ask Claire McCarthy, M.D., your health questions at Parenting.com/momsquad.