By Jane Dreaper
BBC health correspondent
Storing blood from your baby's umbilical cord and placenta is becoming the ultimate critical disease insurance policy for parents.
Umbilical blood is a source of stem cells
The blood is a rich source of stem cells, which may one day be used to treat diseases such as leukaemia.
Private companies offer a banking service for concerned parents.
But doctors have voiced concern about playing on parents fears, and the BBC has learned a group of medical experts is to investigate the area.
A science park on the Downs above Brighton is the storage area for hundreds of samples of umbilical cord blood.
Parents have paid up to £1,500 for the facility, run by Cells4Life.
Among the blood stored here are samples taken from both children of the company's scientific director, Dr Jeff Drew.
"It is a commodity that is normally thrown away - there's no pain, no risk involved whatsoever," he said.
"So I thought if some medical treatment did arise in the future that could take advantage of these things would I regret not having saved them?
"I don't think they will ever be needed but it's nice for me to know that they are there."
Not a hard sell
It is a view much to the fore on the company website, which talks about expectant parents feeling reassured "that they have done everything possible for their children".
However, Dr Drew is open about the fact that the chances of needing to use the stem cells for medical treatment are very remote.
"We try to give as much information as we can. As a company you've got to use a certain amount of salesmanship - but we try to tread the line where we don't overdo it.
"We could sell it to every pregnant woman in the country if we used certain selling techniques.
"But that's the reason why we've only got 300 at the moment - it's because we don't."
Joanna Brown, from Buckingham, contemplated umbilical cord blood banking for her daughter Elizabeth after reading about it on a website.
She says it seemed like a really good thing to do - but she didn't go ahead with it.
"It would have been me who'd have had to have organised with the midwives to take the blood and I thought: 'I'm probably going to be a little bit busy at that stage of things'."
Joanna admits the decision has left her with a feeling of guilt.
"There is a sort of sense of - I don't love my baby £1,500 worth."
Cord blood banks will face increasing scrutiny from next year when a European directive will regulate the way tissue storage is managed.
But experts in the UK already have some misgivings.
The National Childbirth Trust has in the past taken magazine adverts from cord blood banking companies.
However, chief executive Belinda Phipps, is now uneasy about the concept.
She fears that the collection process could affect the final stage of labour:
"When a baby is born - and a minute or so after a baby is born - is a very important time for the new mother and the new father.
"It is a time when they pause, take breath and greet their new baby.
"It is also a time when the midwife is quite rapidly assessing the wellbeing of the new baby and the mother.
"Collecting cells may well get in the way of that process."
Cells4Life wished to point out that it advocates blood collection after the third stage of labour is complete.
Logistical concerns about when the blood was collected were highlighted in a three-page statement from the Royal College of Obstetricians and Gynaecologists.
The paper also said there was an insufficient scientific base to support commercial collection and storage on a routine basis.
But that work was done four years ago. The chairman of the College's Scientific Advisory Committee, Professor Peter Braude, says a group of stem cell researchers and childhood disease experts will produce more substantial advice later this year.
The aim will be to come up with a clear policy for obstetricians, gynaecologists and midwives.
But the most important target will be the public, who Professor Braude believes are vulnerable to being misled.
The companies involved in cord blood banking say they are simply plugging a gap by providing a service which is popular with some parents.
They are bewildered by what they see as resistance in some quarters of the NHS.
Doctors like Professor Braude are not against the idea of stem cell banking - but they would prefer to see a national service with access for all.
"Your doctor would ring the bank and say I have somebody with this particular blood type and tissue type - do you have stem cells that would be suitable to help cure the leukaemia?
"And they would say sure - how much would you like?
"Just think what a wonderful organisation that would be as opposed to all little groups of people keeping some cells for their baby - just in case in the future they might need them."