Dr Catherine Hakim, a sociologist at the London School of Economics, describes them as: "incremental decision makers", women who are constantly reconsidering their options and making their career the priority for another year. "They are constantly postponing, which after a certain passage of time becomes a permanent postponing," she says.
Just how much successful high-flying Nineties women are prepared to sacrifice was made apparent recently by Rebekah Wade when she was appointed deputy editor of the Sun newspaper at 29. "I think I need to be single [for the job]," she said, on taking up her post. Not so long before that she had called off her engagement to EastEnders actor Ross Kemp. Now she has married her job. Would Piers Morgan, who was made a Murdoch editor at a similarly young age, have made the same decision?
A similar trend in the television industry was highlighted by a1994 survey of industry executives which found that 70 per cent of women in their thirties were childless, compared with 34 per cent of their male colleagues.
Ms Wade and her media colleagues are typical of a particular generation - the 20 per cent of women born since the 1960s who are expected to choose to remain childless. This is predicted to rise to 30 per cent by 2010. "In Britain childlessness is highest among women who have most to gain from their careers. They have professional, managerial jobs which offer promotions and interesting work. It's not just the great pay," says Dr Hakim.
But when they reach the top of their ladder, by which time it may be too late to rethink their choices, how will they feel? If lucky they will think like Lisa Gernon, 38, chief executive of Cable and Wireless Mobile, who says: "I opted out of the family life and have never regretted it."
Others believe that a career and relationships are incompatible. Nicola Foulston, 27, last year's Veuve Cliquot Businesswoman of the Year, admits that her regular 70-hour weeks were one key reason her marriage did not last longer. "I tried to find a compromise between my marriage and my business life, but it didn't work out."
Annabel Heseltine, 34, journalist and daughter of Michael Heseltine, the former deputy prime minister, is writing a book about thirtysomething single women - of which she is one. Ms Heseltine lives alone in a flat she owns, like an increasing number of women today.
At 24, Ms Heseltine announced she wanted to travel. "My mother said: `Darling. don't you want to get married?' I said: `Well, yes, but I don't want to hang around and wait for it.' It was a very clear decision and that's the philosophy I've followed throughout my life." Ten years on, she is still single.
She notices how women, herself included, become more picky as about a partner as they get older. "You look at them a lot more closely," she said. "You're not mucking around anymore. You're not 22-years-old, saying: `Isn't it fun.' You are not choosing to be single, but you are choosing to be choosy."
According to Angela Giveon, managing editor of Executive Woman magazine: "A lot of women are making the choice to be single because they realise they can't have it all," said Ms Giveon. "They've usually had a failed relationship - not necessarily marriage - when they make this decision. Something is thrown at them like: `You think of your job more than me,' and they think like a man: `Sod it, it's not worth the bother.'"
But Ms Heseltine remains confused by the apparent priorities of thirtysomething women. She suspects that they are not "really happy". "There are a lot of women in their thirties who seem to be quite happy about throwing away their chance to reproduce, which is phenomenal. There's the selfish gene; is this the selfish generation? ... The reality is that we're put onto this Earth for one reason only and that is to have children. But to deny such a fundamental urge, I don't buy it."
So, we fight for the freedom, but do we really want it? To Ms Heseltine all that choice turns into a burden. "For a lot of women a career justifies them being single. You've had this choice. You want to do these different things. You find yourself single and it's because you have a career."
She believes that, in reality, most of her peers will be married by 40. "It's just taking them a long time to work it out. They are doing the questioning which a previous generation would have done when their children had grown up before they are even married."
But even when the right man does comes along, it is not all done and dusted. "You don't want to have your back against the wall in your mid- forties. In reality, it is six months to a year before you're married. Do you really want to get pregnant the second you are married? Then you need time to try. So you're talking three years. It could all go wrong. The relationship could break up; you may not be able to have children that easily."
Cristina Odone, 37, author and television critic, would like to have children, but does not regret for a minute the choices she has made to date. Unlike Ms Heseltine, she regards careers as assisting women in fulfilling themselves. "I know I would be just as unhappy were I to jettison my writing as to wake up one day and realise I missed the boat as regards childbirth," she says.
However, one incident - "a real eye-opener" - has stuck in Ms Odone's mind. "I went for professional advice to a woman who is a literary lioness," she recalls. "I was writing my first novel. She just looked at me and said: `Just make sure that you don't pass up the chance of having a child. It's my one regret.' It was incredibly poignant and it really did alarm me."
"Some of the most interesting and accomplished women of my age who have foregone the baby option have all regretted it, without one exception. Really, really famous household names. They are all self-styled feminists, self-styled career women, and are all hailed as success stories. Yet, they've all said in private: `There's one thing I regret..."
Between the age of 30 and 34, Ms Odone edited the Catholic Herald newspaper; she made a conscious decision not to settle down and have children at that time. "I was so wrapped up in work, I would have either resented the child or cheated on the work. I didn't want to do either. I don't regret that because I still feel I could have children. It's too early to regret. Now I think I could definitely balance work, which is writing at home, with a child. But hey, where's the husband?"Reuse content