The innocent-looking sitting position that could be harming your child.

Walk into any playground in the world, and chances are you’ll see dozens of kids sitting in the ‘W’ position.

In fact, it’s a sitting position that most kids tend to naturally gravitate to – but experts have now warned it could be doing them serious damage.

The 'W' position - when children sit on their bottoms with their knees bent and legs splayed out to each side, effectively forming the letter 'W' - is now believed to cause serious orthopedic problems later in life.

In a video posted on Aunty Acid, Dr Connie Challoner said the position could damage children's hips, ankles, core stability development, knees and postural muscles.

According to Dr Challoner, the position causes problems later in life as it does not challenge the child's back and abdominal muscles. She said prolonged use could also affect gross motor skills, coordination and balance.

"Because we're not challenging our abdominals and our back muscles to keep us upright, it can cause some weakness in this position. We can also cause some decrease in joint integrity," she said.

She said the key to helping your kids break the habit was to praise and encourage them.

"If you see them sitting in a good position, tell them that's good positioning. If you do see them in a 'W' position, try to get them out of it and assist them into a better seated position," she said.

WATCH for more information on why the 'W' position is so harmful. Post continues after video...

So, what positions should kids be sitting in? Dr Challoner given sitting cross-legged, side sitting (with one leg splayed to the side), sitting with both legs stretched out in front or kneeling with the legs straight behind the butt the tick of approval.

Does your child sit in the 'W' position?