"Dummy use does seem to be on the increase, " says Karen Walker, secretary of the National Private Day Nurseries Association. "It's often on the advice of doctors, who recommend them as an alternative to thumb-sucking. But many children seem to have dummies longer than is good for them."
Earlier in the century, dummies were synonymous with bad parenting. But a quick glance at the baby-care section in any chemist or supermarket shows just how much things have changed. Dummies of every description hang from the shelves - rattle dummies, orthodontic dummies, colour-co-ordinated dummies, even dummies that glow in the dark - fashion accessories as much as comforters.
"They have definitely become more acceptable," says Ms Walker, who believes parents are becoming increasingly lazy in several areas. "Potty training, for instance, is taking place much later than it used to, as is weaning children off bottles and on to cups. Parents just can't quite be bothered getting started."
Prolonged use of dummies may be associated with a lack of supervision and stimulation, believes Mary Daly of the Health Visitors Association. But she insists that in the early weeks they can be a useful survival tool. "Newborn babies are often colicky as their digestive system gets used to food, and dummies are as comforting as anything. Going on about their drawbacks isn't helpful to parents struggling with distressed babies."
But as babies start to develop, they need other kinds of stimulation, she believes. "The dummy holds them in an oral phase - they become very attached to it and don't explore other ways of interacting with the world."
Speech therapists are increasingly vocal in their warnings about the potential impact of prolonged dummy use on language development. Linda Banks, a senior speech and language therapist in Devon, believes continual sucking cuts babies' chances of communicating with those around them. She says: "It's an active discouragement to talk, and they can quickly get out of the habit of babbling and making noises to communicate, which can affect their learning and social interaction. Some children can have a dummy forever and have no speech problems, but it's like smoking - just because some people smoke a lot and never get lung cancer doesn't make it safe."
Speech therapists are also concerned about the effect of dummies on the shape of the mouth, and the child's consequent ability to form sounds correctly. With a dummy or bottle teat filling the front of the mouth, children use the back of their tongue instead of the front, distorting sounds such as "t" and "d", and making it difficult for those unfamiliar with such speech patterns to understand them.
Unfortunately, the fallout from prolonged dummy use doesn't stop at poor communication. Finnish research reveals that attacks of otitis media (acute inflammation of the ear drum) are twice as common in children who still use a dummy between the ages of two and three, and a third more common in the under-twos compared with children who do not use dummies.
But according to Nadine Arditti, a speech and language therapist who has attempted to get health warnings included on dummy packs, the main damage occurs in the mouth. "Incorrect tongue position may affect the developmen t of swallowing, which is linked to problems with teeth and speech development, while babies who suck dummies also tend to breathe through their mouths rather than the nose, which is often associated with dribbling."
Because dummies displace the tongue, she argues, they can cause an oral facial imbalance, with symptoms ranging from headaches to an abnormally developed palate. And with a teat constantly in the mouth, teeth can distort as they come through, leading to gaps. Some dentists believe dummies can also promote tooth decay by causing babies to sleep with their mouths open, leading any sugar or plaque on the teeth to dry faster and build up on the teeth more rapidly.
If that were not bad news enough, recent research from the Medical Research Council has put a new spin on the word dummy. A study of almost 1,000 men and women born between 1920 and 1930 in Hertfordshire, which looked at the links between feeding method and intelligence, discovered that although breast-fed babies were marginally more intelligent, by far the strongest predictor of reduced intelligence was use of a soother.
"Maybe using a dummy makes babies less aware of what is going on around them, or it may be mothers who are not interested in talking to their babies give them a dummy," says Catherine Gale, an MRC researcher. However,she believes dummy use is acting as a marker for home background. "Families from lower social classes were most likely to use dummies, and dummy use was also more common in larger families. Nevertheless, it was a very strong effect, and we don't quite know what to make of it."
Unfortunately, dummies are convenient for parents, and most are simply unaware of the drawbacks. While health professionals can educate parents about the need to relinquish the soother by l0 to 12 months, nurseries and other pre-school organisations should also play their part, says Ms Walker.
"We try to wean the children off dummies during their time at nursery, talking to parents about how we gradually phase them out. We don't take dummies away from children during their first days, but once they settle in we don't have them just sitting there for them to grab. We aim for measured use, such as having a dummy when going for a nap, rather than opting for it as comfort on all occasions. "
But she realises it is often easier for nurseries than parents. "Children can get away with it for much longer at home, but they accept restrictions more from us. Even so, we do have the odd one still using a dummy when they leave to go to school."