Has The World Already Dropped Below Replacement Fertility Rate? New Analysis Suggests We're Having Fewer Babies Than Ever – Even In The Places We Least Expected

But lately, a few studies and models have started surfacing in support of the idea that, fairly soon, the human population really is going to drop precipitously, maybe even halving within just a few decades.

Now, a new working paper from economists Jesús Fernández-Villaverde at the University of Pennsylvania and Patrick Norrick at Northwestern University is going further. The world population isn’t about to start reversing, they argue – it already has. And it’s happening even in the places we’d least expect.

Surprise non-pregnancies

“As of 2026, humanity is likely below replacement fertility,” begins the paper, currently not peer-reviewed but slated for publication in an upcoming edition of the journal Annual Reviews of Economics. “That has never happened before, not in wars or pandemics.”

It’s an announcement that may come as a surprise, even to experts in the field. After all, the most recent official UN statistics put the global fertility rate at 2.3 children per woman, slightly above the replacement rate of 2.1.

Even on a national level, where it’s evident that many countries have dipped below that figure, there are equally many that exceed it – sometimes many times over. Even if, say, Canadian women are only having 1.33 babies on average, surely that’s evened out by their Malian counterparts’ 5.33?

But according to Fernández-Villaverde and Norrick, those figures are unreasonably optimistic. “The WPP [UN World Population Prospects] […] often overestimate births when compared with official vital registry systems,” they argue.

As evidence, they present three countries: Colombia, Egypt, and Turkey – all mid-sized countries with “well-developed vital registration systems," they explain, which are highly rated by the UN’s population center itself.

“Even restricting the analysis to three countries over two years, we find that the UNPD has overstated recent births by over one million,” they point out. “We emphasize again that this is not an isolated example; it looks to us like a systematic pattern of overestimation.”

It’s not a dig, exactly. The UN numbers are based on national statistics and so are only as good as local governments can provide. That’s probably fine for countries with robust administrative systems, but less so in current or recently developing or fractured nations – in Sub-Saharan Africa, for example, “many reported TFRs are more guesswork than hard reality,” the pair write.

All of which is to say: the real surprise of this new analysis is not that fertility rates are falling or even that they seem to be below replacement levels. It’s that this seems to be a global phenomenon – affecting low- and middle-income countries, among poorer and less educated women, just as much as their richer, WEIRDer counterparts.

“Never before have we seen middle-income countries fall below rich countries in fertility,” write Fernández-Villaverde and Norrick.

So, here’s the natural question: why?

A mystery in the bedroom

If you’re hoping for a simple answer as to why fertility rates are plummeting, prepare to be disappointed. In truth, even Fernández-Villaverde and Norrick seem baffled: “we do not understand the mechanisms behind this fast drop in fertility,” they admit, “or its concentration among lower- and middle-income countries and among the poorest and least educated women within them.”

Could it be that reducing child mortality and better healthcare allows parents to invest more in fewer children, as happened throughout the 19th and 20th centuries in the US and Europe? Sure, that’s probably part of it, but it feels like a stretch to suggest this alone accounts for, say, the 35 percent fall in births over 10 years that the pair reports has happened in Colombia.

Similarly, local factors are probably playing some kind of role. It’s well-documented that home ownership – specifically not rental – is correlated with having more children, for example; thus, an unaffordable housing market might produce a lower fertility rate. Some national policies may play a part: in places with more robust family-friendly policies, women are slightly likelier to have more children; in places without, like the US, one or more children may simply be too expensive or time-consuming to contemplate.

But ultimately, none of these explanations are strong enough or certain enough to account for the entire phenomenon as reported by the two researchers. Neither is another usual suspect, the rise of smartphones and social media: “Take Italy,” Fernández-Villaverde and Norrick point out. “Its TFR [total fertility rate] was 1.19 in 1995. In 2025, it was 1.14.”

Such a tiny change “gives you a sense of how much scope smartphones have as an explanation,” they write.

Modern life is adultish

So, what’s the most likely culprit? According to Fernández-Villaverde and Norrick, it’s something far more fundamental and ubiquitous: modernity itself: “Our conjecture is that a modern society makes the third child expensive and childlessness cheap,” the pair write.

In a modern world – one organized around formal institutions, specialized expertise, and large-scale systems of coordination – children are expensive: they require years of investment in education and physical and mental nourishment, and offer basically zero reward, financially speaking.

Gone are the days of more children meaning extra help on the farm; now “children are no longer productive in the household, not even for smaller chores,” the paper states, “having been replaced by ‘engines of liberation’ such as the electric appliances now available even to poor households.”

At the same time, the researchers argue, modernity means living your life according to someone else’s schedule. You work for a large, impersonal organization, and that can make taking a year off to have a baby awkward to impossible. Likely, your parents are in the same situation, so “grandparent duty” is no longer an option either; overall, modernity just makes having and raising babies kind of… difficult.

There is vast uncertainty about the future direction of fertility change. No one knows and no one has a great track record of forecasting fertility

Dr Ronald Lee

And, at the other end of the scale, it’s never been easier to remain child-free, the paper argues. “Modernity makes childlessness cheap,” the authors write, “because an impersonal society imposes next to no penalty on those who have no children.” These days, “pensions and health care do the work that sons and daughters once did,” they propose, “and lineage counts for little.”

There’s more than just lofty theorizing going on here. Evidence from the US – kind of an outlier, in that it has some modern qualities like relatively high incomes and relatively high (for now) gender equality, but some not-so-modern ones like relatively high religiosity – seems to support the idea; so too do the fertility rates of some of the most modernized countries out there – places like China, Taiwan, and South Korea, where fertility rates currently hover around just 0.7.

Add to that the unfortunate mathematics of reproduction – put simply, children come in integers, making even a small change in the actual number of children-per-women produce quite a drastic difference to the overall fertility rate – and it paints a picture in which falling fertility rates are more of a “when” than an “if”.

“In short,” the authors conclude, “modernity in its current form seems largely incompatible with replacement-level fertility.”

So, are we doomed?

The upside of a shrinking world

Whatever happens because of the falling fertility rate, it won’t happen for a while. The population will continue to grow, at least for a few decades; it will likely peak at nine or ten billion; then, it will start falling. None of that is unexpected; neither is it necessarily a bad thing.

After all, not every drop in fertility is something to be lamented. Between 2004 and 2024, the paper points out, the US saw a 74 percent reduction in babies born to teenagers; given the well-documented adverse effects of having or being the result of a teen pregnancy, this change should really only be seen as a good thing.

Equally, a precipitous drop in the world’s population – even something as drastic as cutting it in half – has been touted by some as the only real way to solve many of the ecological and environmental problems we currently face.

Perhaps tellingly, suggestions for how to achieve this can be summed up, at least partly, as “more modernity” – extending family planning into the administrative sphere, so that women can decide how many children they want to have for themselves.

I disagree with them in some ways and would more heavily emphasize their closing sentence: ‘In these waters, the pretense of knowledge is the most dangerous temptation.

Dr Ronald Lee

In short: there’s little reason to panic – especially since there’s basically nothing you can do individually to reverse the trend in any case. And it’s worth pointing out that, as canny as economists may be, they’re not soothsayers: “There is vast uncertainty about the future direction of fertility change,” points out Dr Ronald Lee, a demographist and economist at Berkeley. “No one knows and no one has a great track record of forecasting fertility.”

Lee’s guess is more optimistic than Fernández-Villaverde and Norrick’s: “I personally expect that we are in an extended but transitory period of adjustment of our economies, societies, policies, and cultural values to the new circumstances of our world,” he told IFLScience, pointing to the drastically reduced amount of individual women’s time spent childrearing and vastly increased life expectancies, among other factors.

When the dust settles “my guess is that in two or three decades we will be headed back toward 2 or so,” he said.

But it is a guess, he emphasized – and so is Fernández-Villaverde and Norrick’s analysis. “This is not a crazy paper by any means,” he said. “It is carefully done by very competent researchers.”

“But I disagree with them in some ways and would more heavily emphasize their closing sentence: ‘In these waters, the pretense of knowledge is the most dangerous temptation’.”