The technique involves extracting stem cells from the umbilical cord, which could develop specialised tissue to treat illnesses including strokes, cancers, Alzheimer's and leukaemia, as well as to regrow body parts. The cells are then frozen in vials and banked for up to 25 years.
"It might just save a child's life," said Shamshad Ahmed, manager of London's cord blood bank, Smart Cells.
A growing number of such blood banks have sprung up across Britain, in line with the trend's soaring popularity in the United States. Companies offering them include UK Cord Blood Bank, Future Health, Cells4Life UK and Cells.
Becki MacCullum and her husband, Alistair, last year banked the umbilical blood of their new-born as a talisman against future ill-health. On discovering that statistics cite a one-in-four chance of a sibling match, they paid Smart Cells £1,200 for a kit and 25-year storage plan.
Mrs MacCullum, 35, a City stockbroker, gave birth to their first-born, Freya, on 22 February. In preparation for the hospital birth, she packed her overnight bag with nappies, a nightie, the obligatory babygro - and a cord blood collecting kit.
At precisely 17.17, when her daughter was delivered, Mr MacCullum, 34, a company director, pricked the cord with a needle attached to a bag and drained the blood in less than a minute.
Mrs MacCullum, from Chislehurst, Kent, said: "It's the best present we could buy her. In a few years, she'll grow out of her pram and clothes, but she'll have this health insurance for at least 25 years - it's her perfect genetic match. There are no hereditary illnesses in the family, but you never know what might happen to Freya in the future.
"Her stem cells could also be used to save her parents' or grandparents' lives. There is so little research on stem cells that no one can say exactly how long they can survive - but for £1,200, it's money I am prepared to risk to protect our child's health."
Smart Cells says that in the five years it has been set up, the numbers of expectant mothers requesting the procedure has spiralled. Staff say that they post out an average of 200 kits a month - compared with 140 a month last year, and 100 the year before that.
Mr Ahmed said that cord blood stem cells from an Arab baby boy were implanted last month into his four-year-old sister, who suffers from a life-threatening blood disorder, thalassaemia. She is currently in incubation in hospital in Abu Dhabi, where doctors will learn next month whether the operation was successful.
Stem cells are separated from the blood of the umbilical cord, cryogenically frozen and stored at around minus 126C. They are abundant in the placenta and the umbilical cord, and are particularly useful for treating blood disorders such as leukaemia when a bone marrow match cannot be found.
During embryonic growth they can develop into heart muscle cells, red blood cells and skin cells.
The ability to regenerate human embryonic stem cells without the destruction of embryos would eliminate the ethical concerns of many.
UK Cord Blood Bank - the first private cord blood bank in Britain, which was set up seven years ago - says that it has 1,000 clients on its books. It estimates that 24,000 families across the US have used the service. The company charges £1,500 for the procedure and £875 to freeze and store the cells.
Victoria Strachan, general manager at UK Cord Blood Bank, said: " Harvesting stem cells from the umbilical cord at birth is definitely on the increase in Britain - we are always three years behind America and are now beginning to catch up. We are getting repeat requests from parents expecting their second and third child."
Researchers from Imperial College London have cast doubt on the scheme, arguing that the chances of a child needing such cells are tiny, and collecting them during the birth could distract hospital staff.
Professor Anne Bishop, of Imperial's tissue engineering and regenerative medicine centre, believes that parents should not expect any guarantees.
"It is catching on here, but because of aggressive advertising on the internet," she said. "Vulnerable expectant mothers are being made to worry that if they don't join the bandwagon their baby will die of leukaemia.
"No hospital or company in Britain will provide medical staff to carry out the procedure and midwives are not qualified. Professors here believe it is better to buy the most expensive car seat that one can afford to save a baby's life."
Recent studies by the Leukaemia Research Fund suggests pre-cancerous cells can be found at birth in children who go on to develop leukaemia. Returning umbilical blood to that child may lead to renewed cancer a few years later, they say.
But Smart Cells's Mr Ahmed remains optimistic. "In the next two to five years, there will be a lot more uses for these stem cells. If the cord is not saved at birth, then that is an opportunity lost."Reuse content