At a friend’s house with a group of other mothers recently, the conversation turned to someone we all knew well: married, in her early 40s. But rather than mention her career, recent house move or the fact that she’d just returned from a backpacking trip around Asia, we all exchanged looks and brought up the subject of children – or lack of them.

I was as guilty as the rest of my friends: speculating on her “situation”, wondering if she couldn’t have children or didn’t want to. And if she didn’t want to – why not? Was she career obsessed? Did she not like them? Was she a secret drinker? Cheeks were sucked in and protective, adoring glances bestowed on the toddlers playing at our feet.

But our friend, I’ve since discovered, has simply chosen not to have children. She is happy for her family to be just her husband and herself. She has never felt the urge to be a mother.

Stand-up poet and writer Kate Fox feels the same; her comedy show Good Breeding, about a child-free life, played at last year’s Edinburgh Festival and has been adapted for Radio 4, to be broadcast next spring. “Not having children is as ingrained as my sexuality and I can’t remember a time when I didn’t feel it. Apparently, aged three, I announced to bemused relatives that I didn’t want to have children. My mum even joked about not being maternal and said her mum wasn’t either. I come from a long line of unmaternal women – but my mother and grandmother had more pressure on them to procreate,” she says.

To Kate, it’s more complex than not feeling maternal and she has experienced what she sees as every possible reason for not wanting children. “It’s not that I don’t like kids – I do – but I can’t imagine nurturing one all the time. I also don’t think I’d be able to do what I do in terms of my career and social life if I had children. Then there’s the environment, but if I’d really wanted children, I don’t think that would have stopped me.”

At 39, Kate constantly questions her decision, in case she changes her mind. “I don’t think I will, but I suppose I’m open to persuasion. Doing my show Good Breeding was an interesting experiment in a way: I was surprised how many parents came along and how open they were about their choices. I suppose I’d imagined that people who have children have always wanted them. It’s not that clear cut.”

So has it been an easy decision? “No. It has been a long road to accept myself and believe that I am just as feminine or even emotional without being a mother.

“I think my doubts have been absorbed from both my family and an attitude that’s ingrained in our culture.”

So why do mothers like me and my friends – and many other people – find it difficult to understand the choice that women such as Kate have made? “The child-free have come out of the tributaries of society in the last 10 to 15 years, but the childfree choice is still not totally accepted as an equally valid choice as the choice to have children,” explains Laura Carroll, author of The Baby Matrix (LiveTrue Books 2012), which examines pronatalism, the set of social and cultural beliefs that influence how we think about parenthood.

“The reason boils down to pronatalist social and cultural messaging that has exalted the role of parenthood for generations. When we question pronatalist beliefs and see them for what they are – beliefs – we will also see that choosing not to reproduce is just as normal as the choice to reproduce”.

Tap “#childfree” into Twitter and you could be forgiven for thinking that some sort of revolution is about to take place. Social media, as well as blogs and forums – such as the site We’re (not) having a baby (http://werenothavingababy.com/), the forum Childfree Living (http://childfreelivinguk.yuku.com) and Tumblr’s child-free section (http://www.tumblr.com/tagged/childfree) – are buzzing with discussions about what it’s like to live without children in a family-centric society. But Laura prefers to avoid the word “movement”.

“While the childfree would like to see this choice accepted, I don’t see a collectively organised group out there pushing for this. However, like discrimination based on race, gender, or sexual preference, there is a need for working policies to reflect equal treatment for all employees, no matter who they are or the lifestyle they choose.”

Laura also believes that the media often reinforces stereotypes at the same time as giving childfree families coverage. “Articles with images of a beautiful couple on a beach suggest that the childfree have all kinds of free time and disposable cash to go off on exotic holidays. This is a myth – the childfree come from all walks of life.”

Although the internet has allowed like-minded childfree families to connect, Laura says that sending the message that “childfree” is some kind of new trend is wrong. “For the last decade, longer in fact, the number of women without children aged 40-44 has hovered at about one in five. And census researchers have been saying for years now that the majority of that 20% have no children by choice.”

Miranda Reading, 35, a PhD student, has been married to Tony, 60, for nine years. They have decided not to have children. “Neither of us has ever had the slightest desire to procreate and I think our relationship is all the better for it. As for carrying on a bloodline – we’re happy to be in an evolutionary cul-de-sac,” she says.

Miranda has, however, occasionally turned to the blogs and groups that Laura talks about. “It’s good to know I’m not alone, a freak or abnormal in some way. I think things revolve around children a lot more than they used to. Why are museums and galleries so dedicated to children’s activities that you can’t look at a painting in silence or have a proper adult-level information display? Why are childfree singles and couples discriminated against in pricing structures? And why do politicians assume women are only interested in policies that involve children? I’m more interested in the economy.”

I think back to the assumptions we made about our friend that afternoon, and ask Cass , 28, a childfree television administrator who recently married Andy, 27, about being on the receiving end. “The main preconceptions are that we dislike children, that we are no good with children, or that we have a medical reason which means we can’t have children. All of those are, of course, false – I have friends who have children and I love them all dearly, and as far as I am aware I am perfectly capable of reproducing. I just choose not to, which seems to be something that society can’t get its collective head around so it has to come up with excuses why I must be feeling that way.”

Cass and Miranda have been refused sterilisation by the NHS because they don’t have children already. Cass finds that as she’s in her 20s, people expect her to change her mind. “They assume that once I hit 30, or when my friends start having babies, that’ll be it. I find it quite offensive. As is the idea that it’s not fair on all those poor women who want children and are unable to conceive.”

Cass says that she’s often asked what her husband thinks about it. “As though my decision about my own body is anything to do with him. As it happens, he is fully supportive – when we got together nine years ago he was already aware of my feelings on the matter as we’d been friends before, but when the relationship got serious we had another discussion to ensure we were on the same page.”

Is Andy ever quizzed about his feelings? “Once people discover you don’t want children, they often treat you differently. The reaction can be quite condescending, as if I’m naive and making the wrong choice,” he says.

“I don’t feel that there was a specific point when I sat down and told myself I didn’t want to have children, I’d just never really thought much about it when I was growing up.”

Listening to childfree people talk is thought-provoking and I hope it has ensured I will never jump to the same conclusions about a woman – or man – who isn’t a parent in future.

As a mother, it’s easy for me to list the things that have been hard about my chosen path – the trials of motherhood seem well documented.

I asked Laura Carroll, who is 54, what has been the most difficult aspect of not having had children. “When my friends started having babies, it was hard finding ways to stay in as much contact with them. But that soon passed. My friends didn’t assume that because I didn’t have kids I didn’t know anything about children and couldn’t be party to a conversation about them.

“Also, they didn’t lose interest in what I was up to. With many childfree women and men, when it comes to how having kids can affect friendships, it’s easy to get hurt and feel defensive on both sides. For those with the kids and those without, the key is to not take it personally – to stay in touch with your love for your friends and your curiosity about their lives.”

Miranda agrees that it’s important not to create a distinction between herself and friends who are parents. “We all need to pull together – not find reasons to divide us. Being childfree is a deliberate, often difficult choice, so don’t make it harder by seeing it as a lesser one.

“I admire my female friends with children – I admire their dedication and hard work. I’d like them to start admiring me in return. I work just as hard and am just as dedicated to my own way of life. We are all women. We should be celebrating difference, not creating barriers.”

• This article was amended on 11 October 2018 to remove some personal information.