To celebrate reaching half a century, Gemma Barnes wrote a list of the 50 things she hoped to achieve. Topping it was an ambition that a few years ago would have seemed absurd: she wanted to have a baby. But two years on, Barnes is cuddling her eight-month-old daughter, and while that means most of the other 49 ambitions will have to wait, she is delighted to be a mother.

Barnes’s situation is unusual, but she is certainly not alone. In June data published by the Office for National Statistics showed the number of births to 50-plus women has quadrupled over the last two decades, up from 55 in 2001 to 238 in 2016. During that period there were 1,859 births in the UK to women over 50, and 153 to women over 55. Flying the flag for older motherhood have been a host of celebrities, most recently actor Brigitte Nielsen who was 54 when her fifth child, a daughter named Frida, arrived this summer. US singer Janet Jackson gave birth in January, aged 50, to son Eissa. Perhaps most visible of all has been US Senator Tammy Duckworth, an Iraq veteran who lost both legs when her helicopter was shot down in 2004. She gave birth earlier this year, also aged 50, and was photographed soon afterwards, protesting against Trump’s immigration policies while holding newborn Maile on her lap.

For Barnes, a single mother who lives in London, a baby was always on the horizon but by the end of her 40s several attempts at IVF had failed and the relationship she was in had ended. “I thought, I don’t have time to find someone else, I’m going to have to do it on my own,” she says. Under National Institute for Health and Care Excellence (Nice) guidelines, women over 42 don’t qualify for NHS-funded assisted conception, so Barnes found a private clinic willing to treat her – but the first round of IVF, using sperm from a donor, failed. Then came a conversation that would change everything. “I said to the doctor, ‘Tell me honestly, what are my chances of having a baby at my age?’ And he said: ‘With your own eggs, less than 1%. But if you’re willing to use eggs from a donor, they go up to around 60%.’”

‘It’s still a taboo. Many older mothers feel they are up against it in terms of other people’s views’ ... Photograph: Linda Nylind for the Guardian.

At first, Barnes wasn’t sure whether she wanted to go down that route. “You want your baby to be yours. I was thinking, would she look like me? Would she have my nose? My hair colour? But the doctor started talking about how when you carry a baby you shape so much about his or her personality and behaviour during the pregnancy. I started to think that was right, and that carrying the child was very important.”

Having made the decision to go ahead, there was an egg donor as well as a sperm donor to choose. “You do it all online and it seems a bit surreal, and yes, you do think you’re playing God. These two people will never meet, never know one another, and together their cells will create a baby – your baby. It felt a huge responsibility, especially as I was making decisions all on my own.”

Philippa Hodgson, who is 58 and the mother of a four-year-old, was similarly unsure at first about whether to use an egg donor, but like Barnes went ahead when she realised it would give her the best chance of a baby. She had met her husband when she was 45; her daughter Roxanne was conceived using his sperm and a donor egg. “I was very shocked at first by the idea that we could use another woman’s egg,” she says. “I felt my child wouldn’t really be my own. But now she’s here I couldn’t love her more. Occasionally she does something that I don’t recognise as being connected to either my husband or myself and I think, how beautiful – that must be because of something in her genes from the donor.”

Brigitte Nielsen and daughter Frida, her fifth child, at the age of 54. Photograph: @realbrigittenielsen

Despite being reconciled to using a donated egg, though, neither Barnes nor Hodgson has told everyone in their lives about that element of their story, and nor has the third mother I spoke to, Carol, who is 61 and has children aged 13 and 10. (Barnes and Hodgson are pseudonyms; Carol is happy to use her first name.) Carol’s feeling is that her decision to use an egg donor is not secret information, but it is private – and it would invade her children’s privacy to broadcast it to the world. All three women, incidentally, are entirely committed to telling their children how they were conceived. Hodgson says she talked to her little girl recently about it: “I told her that a kind lady gave me an egg because mummy couldn’t use her own eggs. And she replied, ‘You are my only mummy.’ I was gobsmacked.”

All the same, some professionals working in the field of later-life pregnancy are concerned about what Nina Barnsley, director of the Donor Conception Network, which supports families with children born as a result of donated gametes, describes as a “fog” around the subject, because so few women feel able to be open about egg donation: “It’s still a taboo. Many older mothers feel they are up against it enough in terms of other people’s views, and being open about this would be something else to criticise them for.” Celebrities, meanwhile, are often coy about the precise details of how they conceived, giving rise to the misconception that young people can postpone pregnancy until their sixth decade. “As a society we need to have a proper conversation,” says Barnsley. “The technology means it’s possible to have babies until we’re 75 – but is that what we want?”

Adam Balen, professor of reproductive medicine at Leeds University and fertility spokesperson for the Royal College of Obstetricians and Gynaecologists, shares Barnsley’s concerns. “We’re not very good in the west at preventative medicine, and in the world of infertility we are treating lots of things that could have been prevented,” he says. If IVF has the reputation for being a panacea then that, he stresses, is misplaced. “IVF doesn’t work for everyone, and it’s not available on the NHS for everyone.” As well as being expensive (some of the women I spoke to have spent upwards of £20,000 on their quest for a baby, and anecdotally others have spent far more), late pregnancy carries risks, says Balen. Miscarriage and pre-eclampsia, in particular, are more likely; and the use of donated gametes increases those risks. Stresses around assisted conception can also affect a relationship.

Both Carol and Hodgson have been mistaken for their child’s grandmother; but all three women say they look a lot younger than their years and that few other mothers seem to clock that there is anything unusual about their family. Perhaps, Barnes muses, it takes a woman who feels younger than she is to dive into late motherhood.

Senator Tammy Duckworth, 50, arrives at the Senate with her 10-day-old daughter Maile. Photograph: Jim Lo Scalzo/EPA

For Gemma, being older didn’t mean biting her nails with worry through the pregnancy. “Because the egg was from a younger donor, the risks aren’t so great. I felt fantastic throughout. I concentrated on staying calm, on connecting with the baby growing inside me.” Most older mothers are advised, as she was, to have a caesarean. “It was a very easy birth: it took 10 minutes to get her out, and half an hour to stitch me up. And of course meeting her was so wonderful – I’d waited a long time for that moment.”

For Carol, though, pregnancy was a scary time. “I had miscarried in the past and knew I had a higher chance of miscarrying because of my age. I felt I had so much to lose – it was never going to be a question of ‘you can give it another shot’ the way it would be for a younger woman,” she says. She developed pre-eclampsia towards the end of her first pregnancy and both her babies were born by caesarean. Unlike Barnes, she found that a “very peculiar” experience. Once her babies had arrived, though, she loved the early weeks and months with them. “I felt I appreciated them in a way that you perhaps only do with something that hasn’t been easy,” she says. She struggles to think of any way being older has disadvantaged her children.

“I know plenty of people much younger than me who don’t seem to have much energy,” she says. “I think I do as much with my children as the other mothers I know – I only recently stopped bouncing on the trampoline with them. I don’t feel significantly different from when I was younger.” And then, she says, there are the advantages. “I stopped working by the time I had children, so I’ve been able to put all my time and energy into their lives.” Barnes works part-time, but feels she is able to devote more of her time to her daughter Hannah (not her real name) than she could have done when she was younger. “I’m in a much better place now than I was 20 years ago,” she says. “I’m very settled in myself, very content. I’m fitter than I’ve ever been, I’ve got enough money to be comfortably off and to provide for her. Hannah is everything to me and I don’t have to prove myself.”

Janet Jackson, 50, with her son Eissa in January.

Understandably, the women who are making it work want to concentrate on the positives; they bat off any suggestions that there might be disadvantages. “I don’t feel different from anyone else at mother and baby groups because, quite simply, no one has any idea I’m older,” says Barnes. “Having a baby is a great leveller. When you’re mixing with other parents it’s all about them, how they’re sleeping and feeding and so on. No one asks you how old you are.” Carol is more selfconscious about her age, perhaps because she is now in her 60s and has a child still at primary school. “Telling people how old I am is always a bit scary: you think, will people see me in a different light? I’m very careful about who I share it with. I don’t mind telling friends who have got to know me, but people I don’t know are more likely to judge me in a negative way.”

She has also found her own needs squeezed between those of her children and her parents. “I had a very difficult stage where every time the phone rang I didn’t know whether it would be someone calling from school to say my son needed me or someone calling to say one of my frail parents had fallen down the stairs.” And if her own parents have had their experience of grandparenting curtailed, she knows that is likely to be repeated. “Will I ever be a grandmother? I do wonder about that.” Meanwhile, she says, some of her friends are already grandparents. “It does seem a bit strange, that we’re the same age but in such different situations,” she says.

Barnsley has some concerns about the trend. “Fiftysomething motherhood will only ever be a choice for the well-off,” she says. “And some women will spend a lot of money on something that doesn’t, in the end, work out. Imagine borrowing £50,000 and then being unsuccessful.” She also wonders where the child’s perspective is in the debate. “I’m thinking of 21-year-olds who instead of travelling the world will be looking after a parent with Alzheimer’s,” she says. “They run the risk of being out of sync with their peers, and that might not be easy.” (This is also, of course, the case for men who have children in their 50s and over, although that is less rarely raised as an issue.)

Barnes believes later-life motherhood will become much more common and she welcomes it. “The only two disadvantages, as I see it, are genetics – ie your child doesn’t share your genes – and the risk of dying while your children are still young.” Like Hodgson, she found the genetic issues faded into the background once her baby appeared, although she does sometimes worry about Hannah’s medical history, and what she might not know about it. In the future, she thinks young women will be encouraged to freeze their eggs for later use, as is currently being debated; but at present in the UK human eggs can usually only be frozen for a decade, and fertility specialists say eggs from a woman’s 20s and early 30s would give her the best chance of a child in her 50s. So for egg freezing to be useful, the law would have to change – and some fertility clinics would like to see that happen. Other countries have different guidelines and legislation around fertility, and some British women travel to Spain, Cyprus and India in the hope of making it easier for themselves.

‘You appreciate them in a way you perhaps only do if something hasn’t been easy ... Photograph: Linda Nylind for the Guardian

One thing everyone seems to be in agreement on is that it would be better for young people in particular, and the whole population in general, to know more about fertility. Hodgson wishes she had learned more about it at school. In his role as chair of the British Fertility Society, Balen has called for the curriculum to be widened to teach young people about how to achieve pregnancy, as well as how to avoid it. And yet, one major reason women are tending to leave pregnancy until their 30s is for economic reasons: most twentysomethings can barely afford to pay the rent, let alone provide for a family. Workplace pressures on thirtysomethings to get promoted and zip up the career ladder is another factor weighing against younger motherhood; and however well-informed teenagers become about fertility, there is no guarantee they will meet the person they want to raise a child with before the age of 35.

Kamal Ahuja, scientific director of the London Women’s Clinic, which treats women up to the age of 50 but makes occasional exceptions for over-50s, says that while any doctor would advise childbearing in a woman’s 20s or early 30s, the emotional, financial and social realities, added to the fact that human beings are living “stronger, longer and with greater ambitions” mean the trend is almost certainly set to grow. He predicts that medical advances will make it easier and cheaper in the years ahead.

Gemma Barnes, meanwhile, hasn’t written her to-do list for her 52nd birthday, which is coming up later this year. But when I ask her what’s going on it she smiles broadly and says she is definitely not ruling out a brother or sister for Hannah.