Whether it's Gymboree, Mini Mozart, Baby Yoga or Tumble Tots, as soon as a baby comes into the world these days, there are courses waiting for them.
While the sessions - which normally involve music, singing and playing with apparatus - are no doubt sociable, fun and, let's face it, a good way to fill the sometimes monotonous days spent entertaining a child, are they essential for your baby's development?
Baby Mozart, for example, is a music class featuring live, classically trained musicians which run at various locations in north London. Its website claims: "Frances Rauscher, a renowned psychologist, made waves a decade ago with the discovery that after two years of music lessons, pre-school children scored better on mathematical and spatial reasoning tests than those who took other extracurricular lessons. Interacting with live musicians… aids their cognitive development."
Dr Alexandra Lamont, a specialist in music and child development, says that it is important to expose babies to music but it can be done at home as well as in a group setting.
"Early music classes for mothers and babies, toddlers and young children are an excellent way of providing musical stimulation," she says. "They can help mothers bond with their babies in joint interaction, which is one of the reasons music is such a powerful part of human culture as it allows us to share things physically, psychologically and emotionally.
"Mothers can do all of this at home themselves - we know that almost all mothers sing to their newborns spontaneously, for example - but the groups can provide a structure, as well as providing some social support for all those involved."
But mothers need to be realistic about the effects of these classes. They do not claim to produce baby geniuses.
"We need to be careful about claims that music can drastically improve young children's intelligence or that mothers who fail to take their infants to music classes are somehow neglecting them," she says.
Another franchise on offer is Baby Sensory, featuring textiles and surfaces for babies to play with.
It claims: "The various baby activities aim to build up a vocabulary of sensory experiences (for example visual, auditory and tactile), to enhance physical contact (massage, reflexology, touching, cuddling and rocking) between you and your baby and to promote the development of speech through the use of sign language, music, song and puppets."
The classes, which cost £9 per session, certainly offer a stimulating hour when mother and baby can have fun and meet other parents and children. As child psychologist Dr Richard Woolfson says: "If you want to, go for it. Anything that encourages a parent to play with their baby can only be a good thing. If these classes give parents the confidence to play and interact with their children, that is going to be good for the baby developmentally."
But there are some classes which are rather more expensive. Gymboree takes place in a bespoke "gym" rather than a hired community hall. Each group is led by two teachers (normally from a theatrical background) and singing, soft-play equipment and props are all used to entertain your baby.
Gymboree claims its play-and-learn sessions for 10- to 16-month-olds will help to develop communication, confidence, balance and co-ordination.
A term of 16 play-classes, including the £20 membership fee, at the Gymboree, Hampstead is £250 (or £15.62 a class). It is certainly a slick operation and their costs are probably high but when compared to community-run "stay and play" sessions which cost around £1.50, including a snack and a cup of tea for mum, it does seem rather a lot.
"These classes are a business and people are willing to spend extravagant amounts of money on their babies," says Dr Woolfson. "Be careful of anything that promises a rapid development of a particular skill. Don't expect that it will artificially enhance your child's development. If you think it's going to make him into an athlete or if your aim is that your child will become a genius, you'll be disappointed."
He feels parents already know how to play with their children without the help of a special class. "Parents instinctively know what to do. Your baby requires stimulation every day in the form of playing, talking, laughing, feeding, holding - that is the bread and butter of child development."