birth rates — Alpha.Sources

Freeze the eggs!

Global birth rates are falling at an accelerated pace. According to the UN, the global total fertility rate (TFR) dropped to a record low of 2.25 in 2023 and is projected to fall further to 2.2 in 2024. At this pace, the TFR is set to dip below the replacement level of 2.1 nearly two decades earlier than the UN’s latest forecasts had anticipated.

The long-run decline in fertility has two main components. The first is the "quantum effect"—the trend for families to have fewer children as incomes rise, choosing instead to invest more in each child, particularly through education. Economics and evolutionary theory both rely on this shift in the quantity-quality trade-off to explain why fertility has fallen since the Industrial Revolution, even as wealth has grown.

The second component is the "tempo effect"—birth postponement. Women are delaying motherhood due to rising labour force participation and career opportunities, which increase the opportunity cost of having children, and shifting social norms. Other contributors include difficulty in finding a partner, precarious housing and job markets, and evolving personal preferences. Meanwhile, outright childlessness is increasing, which neither the quantum nor tempo frameworks fully explain.

Demographicsclaus vistesenMay 24, 2025Fertility, IVF, egg freezing, demographics, birth rates, te, tempo effects

Falling global fertility, how far and how fast?

It has been a while since I last delved into one of my favorite topics: global demographics. In this piece, I revisit the subject by examining high-level data on key global demographic indicators from the UN’s July 2024 Population Prospects database. I will begin with birth rates.

Scarcely a day goes by without an article, podcast, or both highlighting the accelerating decline in global fertility. As I explain in my essay on the fertility wars, this discussion tends to divide interlocutors into two increasingly polarized factions. On one side are those who believe falling fertility is a grave problem; on the other are those who remain more sanguine, viewing declining birth rates as a natural consequence of modernity—or perhaps postmodernism—and less of a threat to economic growth, government budgets, or humanity’s survival. If women choose to have fewer children and prioritize careers and personal freedom—long the exclusive domain of men—shouldn’t we support that choice?

The fertility wars

The political flurry in the US over the virtues of parenthood and a high birth rate is part of a much larger cultural moment in which the debate on the significance of falling global fertility is pitting two increasingly militant and unyielding sides against each other. We have trade wars, culture wars, even actual wars; we can now add fertility wars to the list. When Elon Musk, a US entrepreneur and businessman, calls Ms. Harris an “extinctionist”, because she has linked the reluctance of young people to have children to “climate anxiety”, he means it, just as he means it when he concludes that “the natural extension of her philosophy would be a de facto holocaust for all of humanity!”

How to get handle on this? With difficulty, but in the end, hopefully with precision and clarity. First, I will briefly show that the fertility wars have been fought for a long time. I will then draw the contours of three separate positions in the fertility wars today—on the Conservative right, on the left, and a feminist perspective—before offering a suggestion on where this discourse goes next, and where it ultimately ends up, if we are sufficiently unlucky or un-attentive.

Things to think about #4

The Economist’s Free Exchange column drops in on the question of an economic motherhood penalty from childbirth. It is nice to see that the Economist correctly distinguishes between two distinct economic motherhood penalties, both of which can be traced to the interplay between evolutionary forces and modernity, where the latter in this case is defined as an environment with rapidly increasing returns to investment in human capital and education. The first, between fathers and mothers, emerge because the cost of child-rearing especially in the early part of a child’s life overwhelmingly falls on the mother, a conclusion which follows from Trivers (1972). This is true in terms of the cost during pregnancy and immediately after too. It is also true before we consider the possibility that the resource allocation trade-off for many women shifts in the wake of motherhood. The second motherhood penalty occurs between women. Put simply, in an economic structure where childless women have the ability to devote all their resources to somatic investment and take advantage of the above-mentioned increasing returns to human capital investment, the wage and wealth divergence between women who have many children and those who have none will widen significantly, at least in theory. For more on this, I cover the theory in more detail in my essay on fertility and sexual selection; see here.

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