Pippa Middleton’s son is undergoing “osteopathic therapy”. Picture: Reuters

Pippa Middleton’s son is undergoing “osteopathic therapy”.

The 36-year-old socialite - who is the sister of Catherine, Duchess of Cambridge - has said her 12-month-old son Arthur has been seeing a cranial osteopath since he was seven months old, and undergoes the therapy treatment to help him “heal and relax”.

She said: “(It’s for babies) who have had a traumatic birth, are unsettled, or have trouble sleeping. It claims to heal, relax and promote sleep, digestion and body alignment through gentle head and body manipulation. While there is a lack of scientific evidence, after hearing positive things about it (and out of intrigue more than anything else), I took Arthur.”

Pippa - who has Arthur with her husband James Matthews - finds the feedback she gets from the osteopath “valuable”, as she says she has learned so much about her son’s needs.

She added in her Waitrose Weekend column: “I was fascinated to see how calming it was for him, but also how valuable the feedback was. The osteopath noticed one side of his neck was tighter than the other, which explained why he favoured one side sleeping. She also saw that his arms were stronger than his legs, so she gave me an exercise to help him.”

Pippa - who married James, 44, in May 2017 - previously spoke about Arthur’s developments when she spoke about his love for swimming, which she claimed had helped to “improve his digestion”.

She said in April: “Starting my son Arthur swimming at four months old has given him confidence and enjoyment in the water. He’s now 6 months old, and swimming is one of our favourite activities. The exercise helps guarantee sound daytime sleep, and the movement has improved his digestion.”

To a tired new mum, anything that helps calm a crying baby appeals. But is cranial osteopathy as good as its fans claim?

Practitioners say many health problems are caused by compression or distortion of the cranial bones which make up the skull - this can be caused when a baby passes through the birth canal. The theory is that this causes changes to the so-called cranial rhythm, the pulse of fluids and tissues in the brain, which in turn can affect other parts of the body.

Cranial osteopaths claim to be able to feel this pulse in the fluid around the brain and spinal cord and use it to diagnose tensions and dysfunctions in the body.

"The treatment uses gentle, non-invasive techniques to manipulate the head and spine, which affects the whole body," says Kam Panesar, an osteopath from London Osteopathic Care.

Dr Anthony Ordman, a consultant pain specialist at London’s Wellington and Royal Free Hospitals, says "the scientific basis for cranial osteopathy is far from clear". However, he agrees some people seem to benefit from it.

"I suspect it is the effect of a caring human touch that brings much of the benefit, both for the baby and parents alike," he says. It may also help parents to feel they are taking back some control when they had felt helpless.

"As the parents become less stressed, the baby will sense this and become more relaxed too," says Dr Ordman.

Linda Walsh, of the Association of Paediatric Chartered Physiotherapists (APCP), says the association can’t recommend cranial osteopathy because of insufficient evidence that it works.

"The physiotherapy profession requires evidence-based proof of safety, efficacy and quality assurance," she says.