Worrying news for parents who give their children dummies.

Dummies. Lifesavers, right?

Cheap, simple little things that have the magical power to soothe babies. They’ve earned the undying gratitude of many parents. Even better, it’s been proven that babies who sleep with dummies have a lower risk of SIDS.

But there have always been dummy haters out there, and people who have a very firm idea on how old is “too old” to use one. Poor David Beckham found that out when he posted a photo of his four-year-old daughter Harper with a dummy recently.

Even parents who swear by dummies have probably had a niggling worry or two about them as well. Dummies have been blamed for breastfeeding difficulties, increased infections and dental problems.

They've also been linked to delayed speech development. One study found that preschoolers who used a dummy for at least three years, or sucked their fingers or thumbs, were three times as likely to have speech problems.

It had previously been suggested that children who used dummies a lot when they were awake were less likely to join in chatter around them.

Now a new study may have discovered a different reason why dummies can be bad for children's speech development. Researchers at the University of British Columbia got six-month-old babies to listen to two similar speech sounds in Hindi. When the babies had teething toys in their mouths, they couldn't tell the difference between the two sounds. When the teething toys were taken away from them, they could.

WATCH a video of twin baby girls who really love their dummies. Post continues after video...

"This study indicates that the freedom to make small gestures with their tongue and other articulators when they listen to speech may be an important factor in babies' perception of the sounds," said the study's senior author, Professor Janet Werker.

In other words, it seems that if babies can't move their tongues when they hear speech sounds, they find it harder to take them in. This is the first study that's shown this link.

The study authors say this doesn't mean parents should throw away their children's dummies or teething toys. But it does raise questions about how much time babies need with "free" tongue movement for their speech to develop normally.

Would this new research make you think about cutting back on your child's dummy use?