Growing numbers of British women are trying to reconcile the conflicting demands of motherhood and professional life by turning to the controversial technology of egg freezing, allowing them to start a family long after their biological clock has stopped ticking.
Clinics around the country report that up to a third of their patients are now citing lifestyle, rather than medical reasons, for wanting to undergo the procedure, which involves extracting eggs from the ovaries and freezing them in liquid nitrogen until the woman is ready to conceive.
Until now, ovary cryo-preservation, the scientific name for egg freezing, has been used largely for medical reasons, particularly to help female cancer sufferers who need to undergo chemotherapy and are concerned this may affect their fertility.
But, increasingly, women are looking for ways to prolong their rise up the career ladder or the search for Mr Right. Taking time off to have children has been shown to have a damaging effect on professional women's pay and prospects at work. Egg freezing allows older women to become mothers even after the menopause.
The trend is already well established in the US, where private clinics have set out to target single career women.
Around nine fertility treatment centres in Britain have carried out egg freezing since it first became available four years ago. Of these, nearly half say that between one-10th and one-third of their clients have banked their healthy eggs in ice because they are waiting for Mr Right.
The latest figures from Birmingham-based Midland Fertility Services, one of the largest IVF units in the UK, reveal that eight out of 26 egg freezings carried out between January 2002 and December 2003 were for lifestyle reasons.
A similar proportion is reported by the Care clinic at Park Hospital in Nottingham as well as the London Fertility Centre, which last year treated two single women in their early forties who had put motherhood on hold. London's University College Hospital and the Assisted Reproduction & Gynaecology Centre, also in London, report that one out of every 10 procedures last year were carried out on single women freezing their eggs as an insurance policy.
Although egg freezing is a new technique, with only a few hundred British women having undergone the procedure, it offers hope for the Bridget Jones generation, which has put motherhood on hold only to realise that the chances of becoming pregnant naturally after 35 are very low.
The technology of egg freezing has been available in Britain for several years, but it was only in 2000 that the Human Fertilisation and Embryology Authority (HFEA) first gave permission for clinics to thaw frozen eggs. There are now 20 British clinics licensed to harvest eggs from patients' ovaries and freeze them for thawing and fertilising at a later date.
The first successful birth from egg freezing was in 2002, when a married woman gave birth to a baby boy after suffering from fertility problems.
Helen Perry was a patient at Midland Fertility Services clinic, which is run by Dr Gillian Lockwood. Dr Lockwood says egg freezing is being used by busy women who want to delay motherhood.
"They know they are going to be too busy with education, travel, career, getting on the housing ladder so they won't be thinking about starting a family until they are 35," said Ms Lockwood, chair of the British Fertility Society ethics committee. She says critics have accused her staff of "tinkering with nature".
The technique does have an undetermined success rate. Some experts believe it could be as low as between 1 and 10 per cent and that the procedure should not be actively promoted.
Additional reporting by James Burleigh
Considering it: 'I would like to have the option'
Australian-born Hayley Matheson, 22, is single and works in customer services. She thinks that women should have the chance to freeze their eggs as a fertility fall-back for the future and plans on getting her own frozen.
"Everybody should have the option, have the choice to have children if they want to," says Ms Matheson, who lives in London.
"I would rather have the option to think I don't need to rush anything. Australians are a lot more laid back about stuff like this. I know it is a generalisation, but a lot more people here are focused on careers and a lot more people in Australia are less stressed."
Ms Matheson says she wants to have children in the next 10 years but also wants to travel and have a career before then.
"That maybe will take up a good five or six years, which may mean it will be a bit rushed when it comes to having a relationship, getting married and having children," she says.
Against it: 'You shouldn't go against nature'
Rebecca Sampson, 26, dreams of having children - but would never consider freezing her eggs to do so. Ms Sampson, from Earlsfield in London, said she would consider family a higher priority than career once she reached her thirties.
"I don't want to be an old mum," says Ms Sampson, a projects co-ordinator at a major retailer in central London. "I want to have children when I'm still young. My career is more important to me now, but in five years' time I want that career to be my children and family."
Ms Sampson is single, but even if this was still the case in a decade's time, she would not want to freeze her eggs.
"If I got to the stage where I was in my late thirties and still really wanted a child, I'd consider a sperm donor or adoption ... If nature is telling you that you're at the right age and you're body is ready, you shouldn't go against that and try to play God."
Done it: 'My mother and I call it my insurance policy'
Lucy, 39, from Wiltshire has worked hard to build up her career in information technology. But two years ago, she decided to have some of her eggs frozen following the break-up of a long-term relationship that left her single and uncertain about her future chances of becoming a mother.
She says it is a useful fall-back in case her eggs are no longer healthy enough to allow her to conceive when she meets her life partner. "It has given me peace of mind," she says.
"My mother and I call it my insurance policy. That is how I look at it. I am single. I had been in a long-term relationship and I just thought I don't know what is going to happen in the next few years, but what I know will happen is that a woman's chances of becoming pregnant fall really quickly.
"So, now I can just sit back and thank God I have not got to meet somebody tomorrow. When I meet somebody and everything works out, and we think we would like to try for a family, it would be nicer to try in a natural way for a family but in the back of my mind I have this as a fall back."
"It is a very private thing," she says.
HOW IT WORKS
Step 1 Women refer themselves to a clinic where they will be given medical and emotional counselling, followed by a blood test to check whether they are still fertile enough to produce a high number of eggs after ovarian stimulation. At least 10 eggs give a good chance of pregnancy, but a woman of 39 would be lucky to produce six.
Step 2 The female patient then injects herself with hormones for 10 days with a small pen-like gun, similar to those used by diabetics and which is painless to use.
Step 3 The eggs are then removed via a needle through the vagina. This takes less than 20 minutes and the procedure is carried out using painkillers or a mild tranquilliser. The eggs are then stored in liquid nitrogen for up to 10 years.
Step 4 Eggs are defrosted and then fertilised with sperm. Freezing thickens an egg's membrane, making it impossible to be fertilised in the normal way. So doctors will use a technique called ICSI (intra-cytoplasmic sperm injection), where individual sperm are injected into the egg.Reuse content