Jade, 27, shows me the email she’s just received, offering to buy her eggs ‘to help an Asian couple build their dream family’. As a Harvard student who helps me with research, Jade fits the criteria: healthy, attractive, and at a top US or Chinese university. ‘How much?’ I ask. She’s staring at the screen. ‘$220,000.’ Whoah. That’s a staggering amount of money, even if you find the whole thing icky.

Eggs are becoming a valuable commodity in a world where couples are postponing children. Almost a quarter of first-time mothers in the UK are now over 35, an age when our fertility can start to wane. For women scared of missing the boat, many employers are now offering egg freezing: the latest being Chelsea Football Club. ‘You don’t have to choose anymore between your professional career and your personal life being a mum. Now, both are possible,’ Chelsea head coach Sonia Bompastor told Sky Sports.

But while this fashionable corporate perk is very convenient for companies which want female employees to keep working, not disappear to have a family, the deal for women is less clear. It is not a failsafe insurance policy. Success rates for frozen eggs vary widely but rarely go above 30 per cent, according to the Human Fertilisation and Embryology Authority. Many clinics don’t advertise the actual chances of an egg becoming a baby, according to a BBC investigation.

When I started researching a book on falling birth rates, I kept meeting women who’d frozen their eggs to keep their options open. Some have got their own mothers to pay. Others are now going it alone in their forties, using sperm donors, because they haven’t found a bloke who measures up. ‘You don’t want to actually use the eggs,’ says an Australian who froze hers at the age of 29 after coming out of a long relationship. ‘You just want to fall in love with someone and start a family.’

A romance famine is helping fuel a global baby bust. In England, 800 schools are expected to close in the next five years as families shrink. Japan is heading for extinction: one university has a clock counting down the years until the country runs out of children. And the trend is accelerating: Mexico’s birth rate has fallen below that of the US; the UAE’s below that of Germany. At 1.39 children per women, the UK’s birth rate is the lowest on record. If this continues, welfare states will become unaffordable, as pensioners start to outnumber young working taxpayers.

It’s usually assumed that women are turning away from motherhood because they’re prioritising money and career. In fact, the biggest reason women in many countries give for having fewer children than they wanted is not being able to find a reliable partner. ‘Never having met the right person’, is the second most common explanation given by 42-year old British women as to why they’re childless, after ‘not wanting children’ at all. The figures for men are even higher.

Falling birth rates used to be mainly a consequence of couples having smaller families. But in the past two decades, the bigger issue is a decline in coupling up. Gen X and the baby boomers followed a pretty simple pattern: starting a family was the end result of a linear process in which we met someone, then started seeing them exclusively, then moved in together. But among Gen Z and millennials, that relationship escalator is breaking down. In Finland, young couples who move in together are now more likely to split up than they are to have a child.

Dating apps don’t help, with that lingering feeling that there might be someone better out there. One woman told me sheepishly that she couldn’t resist the urge to swipe again while her date went to the loo, even though she liked him. Straight women have been found to be setting their filters at six foot, ruling out a majority of men and prompting potential suitors to overstate their height and other credentials. The problems are compounded by the growing mismatch in the political identities of western men and women, as women move left and men feel marooned, unsure about how to approach relationships. Many don’t get any matches at all. Meanwhile panicking governments shove money into baby bonuses, without realising that the problems can start further back.

The result is heartache: a global disappointment gap between the children people say they wanted and those they had. Studies around the world consistently show that both men and women are ending up with fewer children than they would have liked: some express lower life satisfaction as a result. Low income men are now the most likely to be involuntarily childless, as they fall through the gaps left by deindustrialisation, and the skew of jobs to women in ‘pink collar’ work in health, education and administration. Their stories are some of the hardest to bear.

Dating isn’t the only problem, of course. Housing costs are directly impacting the birth rate, especially in the world’s big cities and especially for less educated couples who need to live near relatives to provide childcare. Expectations of parenting have become absurd, with a crazy roster of extra-curricular activities. Life feels complex and precarious for what I call Generation Maybe. Some analyse deeply whether it’s right to bring a child into this world at all.

Peak human is coming faster than predicted

Children have become an option not an obligation, and that’s a good thing. But the result has a dystopian tinge: Japanese elderly ‘renting’ a grandchild for special occasions, to replace the one they didn’t have; the surge in pets, rather than kids; new products aimed at ‘sperm health’; court cases between neighbours, as children become rarer and their noise less acceptable; students like Jade being sought out for help with conception (she turned the offer down).

Peak human is coming faster than predicted. That will be unequivocally good for the planet. But if the descent on the other side is too fast, the transition will be very painful. What matters most to me is that so many people are missing out on one of the most profound life experiences. Presenting this as solely a matter of ‘choice’ doesn’t capture the full reality of the situation.

Last month, Democrat congresswoman Alexandria Ocasio-Cortez revealed that she was freezing her eggs to ‘feel more in control of her life’. That’s fine, but it adds to a drumbeat which some women feel might become an expectation. Chelsea’s female players might recall that Liz McColgan, the middle-distance runner, won gold at the 1991 World Championships less than a year after giving birth to her daughter Eilish – who is herself a four times European Championships medallist.

When employers and celebrities start encouraging women to put off one of the most profound acts of humanity, by using fertility procedures which may not work, we may have got our priorities wrong.