Virgin founder Sir Richard Branson is set to launch a company which will let families bank and store stem cells from their child's umbilical cord.
Cord blood contains stem cells
Some believe the cells may be used in the future to treat conditions such as Parkinson's disease and cancer.
A handful of UK companies already offer such a service - but obstetricians and midwives say there is "insufficient evidence" to recommend the practice.
It is thought a few thousand couples have already used stem-cell storage.
The service is sometimes promoted to parents through leaflets provided in GPs surgeries and antenatal clinics and also in pregnancy magazines.
Parents can be provided with collection kits which are then taken for processing and storage but some companies send someone to collect the blood.
Virgin says its service is unique because it will offer a charitable element, allowing the NHS to use some of stem cells the company stores.
Sir Richard explained: "We will take an individual's cord blood and we will divide it in two.
"So, part of it will go into a national blood centre that anybody can get access to. And the other half will be put aside for the child."
He said this should help particularly high risk ethnic groups who are prone to conditions that can be treated with stem cells but who may have difficulty finding well-matched cord blood.
The Royal College of Obstetricians and Gynaecologists said it strongly supported the need for an increase in public banks and international accessibility, which the Virgin Health Bank sets as one of its priorities.
But it said a prime concern remained the process of collection of the cord blood and the health of mother and baby.
An RCOG report published last year advised doctors and midwives not to take part in the blood collection as they needed to focus on the welfare of the mother and baby.
They pointed out that the NHS collects up to 2,000 cord blood samples every year for storage in a public bank that can be used by anyone who needs a cord blood cell transplant.
CORD BLOOD STORAGE
One-fifth of stem-cell transplants are done in children and young people with leukaemia
The chance of an individual using personal cord blood for a blood cell disorder before the age of 20 is estimated to be between 1/20,000 to 1/37,000
The NHS cord blood bank has about 7,000 donations
Cord blood storage is also carried out in families at high risk of a condition - such as Fanconi anaemia - which could be treated with a transplant.
Sue Jacob, from the Royal College of Midwives, said the majority of maternity units did not have a policy for dealing with the collection of cord blood, putting midwives in a difficult position.
Half of 267 midwives questioned in a survey by the college said they had been getting requests for the procedure.
She added: "Midwives feel under pressure to engage in an intervention that is not researched or accepted by the profession yet."
Belinda Phipps of the National Childbirth Trust said: "We are concerned about this new promotion of cord blood stem cells collection. The evidence does not show benefits for the baby.
"The method recommended and used by many commercial companies to collect stem cells risks interrupting the birth process, especially the third stage of labour, which is a particularly critical time for both mother and baby.
"Should parents wish to use such services they need to have access to all the information in order to fully understand the risks involved and make an informed choice."