The number of British women aged over 45 who are giving birth has more than doubled in the past decade. This is a greater increase than is found in any other age group.
Advances in fertility treatment and the fact that many women are focusing on their careers before settling down to motherhood has produced a record rise in older mothers.
New figures show that 1,091 women aged 45 and over gave birth last year, compared with 540 in 1995. The statistics include those giving birth for the first time.
These findings from the Office for National Statistics are in stark contrast to the significant dip in the number of women choosing to have children in their twenties, although younger mothers are still in the majority.
Ten years ago, nearly 350,000 women between the ages of 20 and 29 gave birth. That figure has now fallen to below 300,000.
Yet the number of women over the age of 40 giving birth has nearly doubled from 11,319 10 years ago to 22,246 last year.
The list of high-profile women who are experiencing motherhood in their forties includes Madonna, the actress Emma Thompson and Cherie Blair, who was 45 when she gave birth to Leo, her fourth child. And yesterday a 67-year-old Spanish woman became the world's oldest new mother when she gave birth to twins after IVF treatment.
This newspaper reported last month how the trend in older mothers is also influenced by the fact that women are going through the menopause 18 months later than they did 50 years ago. The average age of menopause is now 50.5 years compared with 49.1 for women born in 1915.
But experts warn that older mothers face significant health risks in delaying childbirth and that many women who leave it until their forties will suffer the heartbreak of infertility.
The age limit for women who seek fertility treatment on the NHS is between 38 and 40, which means that older couples have to pay privately if they want to become parents.
In theory, any woman who is menstruating can conceive. But the chances of a woman getting pregnant in her forties are drastically reduced, and the older she is the greater the risk of miscarriage, birth defects and high blood pressure as well as complications in childbirth.
Gynaecologists also say they are under increasing pressure because of the "precious baby" syndrome, where pregnant women who have delayed motherhood are so anxious about complications that they insist on giving birth by caesarean section.
Dr Gillian Lockwood, who runs a fertility clinic in the Midlands, said that increased life expectancy and improved medical care meant that there was no reason for women not to give birth later in life.
But she also warned that many who leave it until their late thirties and forties face the heartache of infertility because they are lulled into a false sense of security that their reproductive systems are as young as they feel.
"Given life expectancy, I see no particular problem with women extending the time in which they have babies," said Dr Lockwood, medical director of Midland Fertility Services near Wolverhampton.
"But I think it's vital that women recognise - even though, in their late thirties and forties, they look and feel so young - their ovaries may be past their sell-by date." Dr Lockwood also warned that, although some older women will be able to conceive one child, they will be disappointed when they cannot have a second.
"They think 'that was easy' and two years later want a sibling and discover it's not happening. Then they press the panic button."
Dr Peter Bowen-Simpkins, from the Royal College of Obstetricians and Gynaecologists, said that the health risks are substantially increased for older mothers. But he pointed out that the trend is no different from the Victorian era, when it was common for women to give birth in their forties, although most would already be mothers.
"Medically speaking, the best time to have your baby is between the ages of 21 and 25 and the chances of complications is increased if you leave it until late in life," said Dr Bowen-Simpkins, co-medical director of the London Women's Clinic.
"But I don't think older mothers place any burden on society - 40-year-olds today are much fitter and are more likely to be able to afford the cost of parenting."
Additional reporting by Paul Bignell
ONE MOTHER'S STORY
Pamela Laycock, 50, had her son Toby at the age of 45.
As a teenager, Ms Laycock assumed motherhood would begin in her early 20s - that she would meet someone at 21, marry soon and be a twentysomething mother.
But now, Ms Laycock, 50, a successful career woman, doesn't regret not having her first child until she was 45: "I think being an older mum certainly means you've got more experience to draw on. You've probably got all those things out of your system - like travelling. If someone had told me at the age of 15 or 16 that that wasn't going to be the case, I would have been absolutely mortified. But in hindsight I'm very pleased it turned out the way it did."
Ms Laycock and Derek, 48, her partner of 16 years, had son Toby, six last Sunday, through IVF. Despite spending some £14,000 on treatment, she was delighted when it was successful after two attempts.
"I probably have more energy than most, but I made a conscious decision that, after the age of 45, I would have given up trying."
Pros And Cons: Three women who left it late
Patricia Hodge The Lincolnshire-born actress, well-known for her role as Phyllida Erskine-Brown in Rumpole of the Bailey, gave birth to sons Alexander and Edward in her forties, after 12 years of infertility. Hodge is realistic about some of the drawbacks of being an older mother: "If you have children in your twenties when you are still young and active, you can run around with them all day. I dread to think how I will feel when I am in my sixties and having to deal with adolescents."
Emma Thompson The Oscar-winning actress and star and writer of the film Nanny McPhee gave birth at the age of 40 to a healthy, 7lb daughter, Gaia Romily. Seven-year-old Gaia was conceived through IVF treatment by Thompson with actor husband Greg Wise. Thompson recently spoke of her depression after she tried to conceive a second child through IVF.
Dawn Airey BSkyB's controller said last month that she was to become a mother, after her lesbian partner Jacquie Lawrence announced she was pregnant. Ms Airey, 46, has shared a home with Ms Lawrence, a film-maker and gay rights activist in her forties, for four years. Ms Airey and Ms Lawrence are said to be "absolutely thrilled", and according to friends, can't wait to become parents.Reuse content