JESSICA Hepburn doesn’t think the bruise will ever disappear, the psychological one that still hurts whenever she hears the news that someone is pregnant or has had a baby. “I’m not going to pretend it’s ever going to go away,” says the fertility campaigner, blogger and author. “When I hear pregnancy announcements, the pain is still hard. Because I wasn’t the lucky one. And it has a lot to do with luck.”

At 46, Hepburn has all but entirely given up hope of having her own baby. If hard work had been what it took, she would have got there by now, for few people can have made tried so hard, going through 11 rounds of in vitro fertilisation (IVF), all unsuccessful, spending £50,000 on treatment, getting herself into severe debt, and finally giving up when there was no money left.

Partly, she stopped trying because of the money. But also, she decided to draw a line under her efforts because she was then 43, and remembered a friend's advice: “If you haven’t had a baby by the time you’re 43 you might as well get on with the rest of your life.”

She recalls that watershed moment. “I didn’t believe it was going to work anymore.” Rather than try a fresh route, of donor eggs, she followed her friend’s advice, and got on with her life, throwing herself at the opportunities that were there for her.

Her book, The Pursuit Of Motherhood, was published that year. It told, with astonishing frankness, the story of her journey, with her partner, Peter, through the fertility industry, from their first attempts to get pregnant, through a diagnosis of “unexplained fertility” and treatments that began with artificial insemination and escalated to ever more expensive rounds of IVF. “When my book came out, my life took off in a different way," she says. "It weirdly saved me.”

Hepburn has now left behind her own intense pursuit of motherhood, and instead committed what she imagines will be “a decade” of her life to being a fertility campaigner, setting up an arts festival called Fertility Fest, writing her blog, talking to schoolgirls about fertility, speaking at events like the one she is chairing at the Edinburgh International Science Festival this Tuesday, which brings together experts including bioethicist Dr Calum MacKellar, Susan Seenan, Fertility Network UK's chief executive Susan Seenan and Dr Marco Gaudoin from Glasgow Centre for Reproductive Medicine.

Hepburn once ran out of an artificial insemination session because she was gripped by the paranoia that the sperm may not be her partner’s, but that of another man. Her most terrifying moment came when she was rushed to hospital with a life-threatening ectopic pregnancy. In a four-hour theatre session, surgeons struggled to find the foetus, searching in various parts of her abdomen, finally finding it in her stomach.

Hepburn is in a hospital as we talk, visiting her mother who has just had a hip replacement. It’s the run-up to Mother’s Day, one of the times she becomes acutely aware of that yearned-for thing she doesn’t have. “Who’s going to look after me, Mum?” she asked her mother earlier. “Who’s going to bring me to hospital?”

The number of women who are in their mid-40s and childless, or child-free, has doubled in a generation. “Of course,” says Hepburn, “some of them have decided not to have children but a lot of them haven’t and there are a myriad of reasons. Medical infertility, not meeting the right partner, meeting someone who doesn’t want children.” Age-related infertility is “the number one reason for the exponential growth of the fertility industry”.

When Hepburn talks to young women and girls she is keen to emphasise that fertility declines with age. “I think we were slightly cheated by feminism," she says, "because we were told we should focus on our careers in our 20s and be picky about choosing a partner, then have children in our 30s. For most people that’s fine. But you are then in the latter part of your fertility lifecycle, and if you do discover you’ve got a problem you’re running out of time.” For a woman, she notes, the best age to start having a family, to have a chance at the family size you want, is 25.

Hepburn was 34 when she started trying, at first casually, for a baby. She went through her gruelling seven-year ultrathon of treatments, all the while holding down a demanding job running a London theatre, the Lyric Hammersmith.

For the most part she kept the rollercoaster she and her partner were going through a secret, not only from colleagues but also from her family. Her mother only found out what she had been through on the day she was handed The Pursuit of Motherhood. “It was really hard for her to read what I’d been through," says Hepburn. "My dad died before the book was published so he didn’t know any of this.”

Coming out about it has been “good” for her family. “I know my mum finds it really heartbreaking that I’ve not been able to have a biological child, but she can tell me that now and it’s OK. Because it’s the truth. It is heartbreaking for her and heartbreaking for me.”

Such secrecy around IVF is commonplace, she says. “We’re dealing with a subject that is often shrouded with secrecy and shame. Many women feel like they’re not proper women because they can’t conceive. I always say in my talks that infertility is bound up with shame, and shame breeds in silence. So you’ve got to call it out all the time.”

Next year is the 40th anniversary of the birth of the first IVF baby, Louise Brown. Medical science has since brought many longed-for children into the world. However, Hepburn’s is concerned that some of the new technologies, amazing as they may seem, are not as yet proven to be entirely effective. “These technologies are so new and there’s rather scant evidence about whether they work, yet, obviously people are investing their future happiness in them.”

She is also sceptical about the enormous efforts that couples make by going on extreme health regimes. “You see people who give up everything – alcohol, coffee – and only eat broccoli and kale shakes. Their life is dominated by this. But the reality is, is this broccoli and kale shake going to get you pregnant? No. The single biggest thing that matters in fertility is age.”

IVF rarely works first time. Only one-third of all cycles are successful, though almost half of patients succeed by their third cycle. This, says Hepburn, “is why Nice [the National Institute for Health and Care Excellence] recommend that people have three cycles, and why it’s so scandalous that so many places in England don’t offer that.” Last week, the Scottish Government, announced that it had put aside money to fund three cycles of IVF.

Hepburn’s own story represents only a very small percentage of people. She kept on going, after many would have given up, partly because she has enormous reserves of grit, and partly because she was getting positive signs that it might just work. “We had a lot of indicators which suggested we could get pregnant – lots of miscarriages and an ectopic pregnancy. Generally doctors consider if you can get pregnant eventually you will stay pregnant.”

In an article for the Daily Mail, she wrote that she believed the ectopic pregnancy tipped her “over the edge”, changing her “from a woman doing all she could to fulfil her dream of motherhood into one who became consumed by it”.

Each time the treatment failed, she would be hit by a new wave of grief. “The only way I could get through it was to start the treatment from a position of thinking it wasn’t going to work, to protect myself from disappointment. But when you do that, you think am I somehow jinxing it?” At one point, she became convinced that the problem was not her body, but her mind.

All of this took its toll on her relationship with Peter – which, she says, has “staggered” in recent times. “We have been through quite a hard time. We’re soul-mates. We’ve been together for 16 years and will always be in each other’s lives, but we have been through quite a struggle over the past few years.”

Hepburn’s story is not just one of loss, however. Mostly what she conveys, both in her writing, and life, is that motherhood is not the only source of meaning for a woman. When she gave up on fertility treatment, not only did she start campaigning, she also began doing big endurance events. She swam the Channel, did the London marathon, and climbed Mount Aconcagua, the highest mountain in South America. “That saved me,” she says, “I realised this thing that I wanted to happen isn’t going to happen; I need to make the most of this short life I’ve got in a different way.”

When she swam the 21 miles of the Channel, she decided she would meet 21 women, half of them mothers “in all sorts of ways – adoption, egg donation, natural”, and half of them not, and write about it. The book, 21 Miles To Happiness, to be published next year, will be “about female solidarity, motherhood versus non-motherhood, life fulfilment”.

“What I was trying work out," she says, "was – does motherhood make you happy and can you have a fulfilling life without children? I realised there are many ways to be a parent, but also that people often need other things in their life – and there are lots of other fulfilling things to do with life. At the moment I’m living the most fulfilling life without children.”

Sometimes she tells herself to relax. “But when I do think about backing off I just think, yeah, but how many years have I got left?”

Jessica Hepburn chairs The Fertility Computer, an event at the Edinburgh International Science Festival on Tuesday, April 4