My friend Anusha, a 28-year-old retail analyst, is another "birth striker", deciding when she was about 21 that she didn't want to have children. "At the time lots of friends and family told me that as I got older, the biological clock would start ticking," she recalls.
"But actually the opposite has happened. The older I've got the more my decision has solidified. There are now a lot of wider issues that I'm passionate about in terms of the planet and climate change that have confirmed that decision for me. Beyond not eating meat, recycling, using public transport, the number one thing that you can do for the planet is not reproduce."
Anna Hughes, a cycling instructor and author, agrees. "It's inescapable that having kids... creates a resource-consuming person," she says, adding that if she were to fall pregnant, "I would have an abortion."
Interest in halting procreation for the sake of the planet is growing. Population Matters, a charity that addresses the effect of population size on the environment, has seen its online traffic and social media following soar, with a Facebook post on going child-free reaching four million people.The charity maintains that "smaller families mean better lives for all", and cites Thailand, a country which reduced its fertility rate by nearly 75 per cent over two generations with a targeted family planning drive, is a model we should be following.
Beyond not eating meat, recycling, using public transport, the number one thing that you can do for the planet is not reproduce.
The BBC is currently exploring the debate over slowing population growth via its Blue Planet Live tour and a forthcoming series of documentaries, Protecting Our Planet. "The single most important thing to deal with is population growth. We're just simply running out of resources," said Chris Packham, who presents one of the films. "Do you want to bring something you will cherish and love and value into a world where they might no longer survive?"
The dilemma has not been lost on my friend Kate, 36. Since the birth of her first child, Raph, four months ago, she has become more eco-conscious. "I'm worried about his future and 80 years down the line is looking pretty bleak, so the issue of overpopulation would definitely make me think twice about having another." As such, adoption has become a consideration in answering a possible future desire to reproduce, she says - and, "if I do have another child, I would want to raise two individuals who are equipped and want to do their best for the planet".
Overpopulation leads to severe economic problems too, says Suzanne, 28, who works in marketing and has also chosen not to have children. "I just don't feel that the world needs more people," she says. "The way cities are expanding so rapidly produces cheap labour and keeps wages down, and that means competition for resources. It's not a world in which I would envision wanting to raise children... I don't want to add to the problem."
Sometimes, it has been uncomfortable explaining her decision. "I'm not in a relationship right now, but it's something I'm aware of when those questions come up - and some men have been put off by it. It's always a difficult conversation to have."I know this all too well - over the years my zero-child policy undoubtedly ended relationships. After a few dates, we would have the conversation and I would explain that children just weren't part of my life plan. Usually we would go out a few more - subdued - times while she thought it over, but then more often than not she would say that forgoing a family would be too hard, and it would be best if we left things.
Of course, emotional urges to have a child may always overtake environmental ones and, over the years, friends and family have tried valiantly to change my mind with the usual arguments: "Children will look after you when you're old", "they keep you young", "you'll have fun with them". When I told my mother I was sure I didn't want them she was disappointed, but at least my brother had reproduced, so that took some of the heat off me. It didn't stop her from holding up pictures of babies in magazines in a silent attempt to persuade me otherwise, though.
I am now in a relationship with a 37-year-old woman and, for the first time, find myself beginning to waver ever so slightly from my decision. I can't say what caused it, but perhaps I have just reached the point at which a visceral urge trumps a thought-out argument - even one I've maintained for decades. From time to time, I'll see a father with his son, talking about castles or Gothic literature or spies, and something inside me kicks. It says I should be there too, making up explanations for how birds stay in the air.
My position hasn't entirely reversed, but I suppose mine and my girlfriend's respective ages mean that if we're going to do it, we had better get on with it. She knows that I used to be firmly against having offspring, and the vestiges of that preference can be a worry for both of us: what if it turns out in the end that I'm not cut out to be a father after all?
It's a risk. And I haven't told friends or family that I may renege on my birth striker status - it seems too personal, somehow. I'm going to just let it come out if and when the issue arises.Yes, the intellectual case against having children, the worries about their future on an overpopulated planet and my ability to provide well for them, are still there. Yet times change, and maybe I have, too.
