W Sitting can cause negative effects.By Kim BradleyW sitting is when a child sits on their bottom with their knees bent and their feet positioned outside of their hips. It’s called W sitting because when you are standing in front of them, their legs make the shape of a W. When your child is playing, typically they will move in and out of various positions. This is normal to sit in various positions including W sitting. However, if your child prefers this position and sits in it for extended periods of time, there can be negative effects.First, W sitting promotes poor posture because it doesn’t require your child to activate their core muscles. W sitting does not challenge a child’s balance and more importantly does not allow them to ‘weight-shift’ effectively. When your child is W sitting, they may be compensating for these weaknesses because it provides a wider, more stable base of support. Your child may be using this position because he does not have enough core strength to balance adequately in typical sitting positions.W sitting can also be very limiting to your child during play. Once they are sitting in that position, it’s much harder to change positions easily and turn their body, go from sitting to lying and kneeling, and move on and off the floor. More seriously, W sitting can cause the muscles in the hip joints to become very lax and in more severe cases, if those joint stabilizing muscles become too loose, it can lead to hip dislocation.It should also be noted that W sitting is much more common when children have decreased muscle tone–when there is not normal muscle resistance at rest. Kids with low muscle tone may have muscles that feel ‘mushy’ or ‘floppy’ when you hold or move their arms and legs around, whereas normal muscle tone would provide some resistance. If my child W sits, what can I do?Come up with a word or a visual cue (such as a hand gesture) that you and your child establish together to cue them to move out of W sitting.Have your child use a chair, stool, or riding toy during those times when you observe frequent W sitting. This might include playing, watching tv, or having a snack. If your child participates in these activities while on the ground, move them to a child-sized table and chair.Balance cushions that are inflatable, pillows, or small exercise balls are fun seating options to offer your child. These types of options are fun and also great to work on sitting balance and core stability.Promote and set examples for other sitting options, such as tailor sitting, ring sitting, long sitting, side sitting, sitting with legs criss crossed, or kneeling.If you have additional concerns regarding your child W sitting or are concerned that your child might have decreased muscle tone, consult your pediatrician or pediatric OT or PT. Kimberly Bradley is a licensed pediatric occupational therapist who writes our column, "Wiggle Room." Check out her latest article, "Breaking the Container Baby Syndrome."