In a world awash with angst about Penelope Leach and the latest breakthroughs in fertility treatments, “I just don’t want kids” is not a line you expect to hear. But there is a sizeable number of women who have deliberately chosen to bypass the whole baby thing — and their number is growing: as many as one in five British women now opt to remain child-free, compared with one in 10 in the mid-1960s. And we’re not talking about the “maybe one day” mums waiting for the right man, or moment in their career, to materialise before they toss away their packet of pills, or indeed, those who don’t have a choice, but women who have made the positive decision not to start a family. They are not unnatural or selfish, and they don’t hate kids. In fact, their reasons for remaining child-free are as many — and as valid — as the reasons for having a baby. For some, it’s about lifestyle and their relationships. For others, it’s about money. A few feel the world is overpopulated enough.

Most talk about it openly, although often defensively, because they believe there is still a stigma attached to admitting you don’t want children. When we come across a screaming toddler in the supermarket, we all breathe a sigh of relief that it is not ours — and where, they ask, is the shame in that?

Katie, 45, is an actor, and has been married to Mark for 16 years. They moved from London to New York four years ago. She decided not to have kids to preserve her lifestyle and happy marriage

“It’s not that I don’t like kids, it’s that having kids and raising them is a life that’s not for me. When we first got married, we both assumed we would want children, and that it would happen at some stage. Each year, we made a point of sitting down to discuss it, but every time, we said, ‘No thanks, not right now’, and got on with our lives and careers. I never had that thing when you get to 40 and suddenly realise it’s too late. I am as sure of my decision not to have children as I am of my shoe size.

“Whenever we talked about it again, we had become a bit more established in our careers; we had a bit more money, and had become a bit more accomplished — and we were happier together. That was always the proof that we had made the right decision. Meanwhile, we looked at friends who had kids, and there was nothing about their lives that we aspired to.

“The great thing about our life is that it is as if we’ve never settled down. We knew London better than all our friends; we were members of societies; we went to the theatre, cinema, exhibitions and galleries; and we regularly tried new restaurants. We felt we were really able to live our lives to the fullest in a way that our friends stuck at home with children simply couldn’t. The way we see it, having kids ruins your life. When Mark received an offer to move to New York, we were easily able to get up and go because it was just the two of us. Mark is sometimes at work for 12 hours a day these days, and I know that if I was stranded at home with children, I would be totally miserable. Instead, I am pursuing an acting career, which I gave up after studying drama in college for a steadier job in sales. To have a second chance in my mid-forties at the career I have wanted all my life is just a dream come true.

“I think it’s great for people to want to raise kids, and I don’t condemn them, but I don’t expect them to condemn me, either. What annoys me is people who have children, then spend the whole time moaning about how hard it is — as if it’s a surprise to them. I think it’s more selfish to have kids because you want a piece of yourself in the world — then treat them like an inconvenience.

“I also get angry when people say women who don’t want children haven’t found the right partner. That’s a direct insult to Mark and me. For us, it’s simply that we are so happy together, we don’t need anyone else. Some people say that if you have a child, it completes a marriage, but we don’t feel there is anything missing.”

Heather, 29, travels and teaches English in Asia. She is single. She believes having kids would be unfair on them, given her lifestyle

“I love to travel and move around a lot, and I don’t think that kind of instability would be fair to a child. I look at my friends who have kids, and they are hard-pressed to be able to go on a two-week holiday. I know I would go mad if I couldn’t up and leave for however long I wanted, whenever I wanted. I really look at their lives and think, how boring. When I am running around the jungle, swimming in the sea, painting a picture, writing in my journal, dancing till dawn and making plans, I am so relieved that I don’t have a baby in tow.

“Nor do I want to give up my life for another person. I know this sounds selfish, but I think we often avoid knowing ourselves completely by diving into someone else, whether that is a child or a partner. I think it’s hard for a mentally healthy woman not to become obsessed with her babies, and I want to put my energy into other things.

“Living as a long-term traveller has also helped me make my decision. I don’t feel good about bringing another child into a world that has so many problems already. We should focus on looking after the children who are already here. Of course, I have been warned that when I reach my thirties, I might start to panic about having a baby. But to me, this sounds like pure hormonal desperation and a terrible way to decide to have a child.

Times recommends

• Are eldest children really a cut above?
• Peaches Geldof: censored
• Top 10 style-setting films of all time