The bad toddler habit Prince Louis' picked up

The Duchess of Cambridge has once again illustrated her unflappable parenting prowess by gently stopping her youngest son from sucking his thumb.

On Saturday, Prince Louis made his Trooping the Colour debut, and his royal cuteness won the hearts of the nation by sweetly waving to the crowds on the balcony of Buckingham Palace.

Adorably, the 14-month-old revealed a very common habit among children his age – sucking his thumb.

Throughout the day, the tot was seen slipping his thumb into his mouth including while looking out the window from inside the palace with his two siblings, Prince George, five, and Princess Charlotte, four.

But when Louis started sucking his thumb during his balcony debut, the Duchess of Cambridge’s mum reflex kicked in and she gently stepped in to try and stop him.

When husband Prince William was holding Louis, he attempted to remove his son's thumb gently, but spotting the interaction, the mum-of-three smoothly approached Louis with a smile and effortlessly eased his his thumb out of his mouth.

Little Louis then went on to continue his charm offensive by clapping and waving to the crowds.

According to the British Orthodontic Society [BOS] thumb and finger sucking is one of the most common habits developed during childhood.

They say there are two reasons why your child might suck their thumb; the first is for comfort and the second is that it is a learned habit.

Thumb sucking can begin as young as three-months-old (having originally started in the womb) but can persist for years.

BOS statistics reveal one in every eight children in the UK (aged 7 to 11) has a prolonged thumb sucking habit.

Generally experts believe that children usually stop sucking their thumbs when they become more self-sufficient at around two years old, but there are a couple of concerns if children do continue to suck their thumb.

The first is that children, who often aren’t practiced in good hand hygiene, will transfer germs directly to their mouths from their hands.

And the second is to do with the development of thumb suckers’ teeth.

The NHS advises that both dummies and thumb sucking “encourage an open bite” (when teeth move to make space for either object).

"When most people think about reasons for orthodontic treatment, they're thinking about the problems you can easily see – protruding teeth or teeth that overlap each other, for instance,” explains Dr Thais Booms of Beyond Braces: A Consumer's Guide To Orthodontics.

“But every bit as important is the bite, and while problems with your bite aren't always as noticeable, they do have consequences."

Left uncorrected, an uneven bite can lead to numerous problems, including headaches, broken teeth or gum recession.

“Prolonged thumb-sucking or the use of dummies (pacifiers) beyond the age of 4 increases the risk of altering the bite,” Dr Booms explains."In a proper bite pattern the upper teeth slightly overlap the lower teeth. But dependence on thumb-sucking or a pacifier for extended periods can prevent that from happening.

“The back molars may touch when the jaws are closed but the front teeth don't. And the frequent presence of a thumb, finger or pacifier while the two front adult teeth erupt can cause them to come in improperly."

According to the BOS, a dummy habit is easier to stop and those who are given a dummy at a young age are far less likely to suck their their thumb.

So what can parents do if they want to discourage thumb sucking?

The BOS suggests first stopping the habit during the day.

They believe encouragement is key and suggest using a reward chart to help children to cut down then stop.

Praising a child for not sucking their thumb is also recommended as is avoiding nagging, teasing, punishing or shaming a child.

Like the Duchess of Cambridge, every parent should approach thumb sucking and when to tackle it in the way that best suits them and their children.

Just like toddler tantrums, thumb sucking is just one of many parenting conundrums even royals have to tackle.

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