Are Western Fertility Rates Really Collapsing—or Are We Measuring Them Wrong?

Very interesting article by The Economist on fertility rates across the West over the past few decades. The commonly accepted view is that fertility has fallen significantly below the replacement rate (2.1 children per woman), implying that population decline in these regions is inevitable in the not-so-distant future. This article argues that the gap may not be as large as it appears, and that part of the issue lies in how the phenomenon is measured. In a nutshell, it comes down to the difference between Total Fertility Rate (TFR) and Completed Fertility Rate (CFR)—and how each is calculated. Put simply, the first indicator (TFR), which is the most widely cited, does not account for the fact that women are having children significantly later than in the past. This “tempo effect” skews results toward more dramatic declines. The second indicator (CFR) corrects for this timing issue. While it still shows a decline compared to the past, it is far less severe than what TFR suggests. From a data science perspective, this is a useful reminder: you always need to understand how your KPIs are constructed before interpreting trends. Otherwise, you risk mistaking timing effects for genuine macro-level shifts. The “sentient lizards” parable used to introduce and explain these concepts is a small masterpiece. Highly recommended reading. (text revised by a LLM) Watch who you’re calling childless https://www.economist.com/finance-and-economics/2025/12/18/watch-who-youre-calling-childless From The Economist

- Pedro

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