Fertility Shifts Compound Across Generations

Updated: 2025.08.24 1M ago 7 sources
Small policy-driven changes to birth rates don’t stop with the first cohort; they ripple as those extra children later have children of their own. Even a 3–6% swing in births can yield much larger multi-decade population effects once compounding is included. Demographic accounting should routinely include this propagation, not just first-order changes. — It provides a general heuristic for evaluating family policy, abortion law, and pronatal incentives by highlighting long-run multiplier effects.

Sources

From Longevity to Low Fertility: Evidence Across Countries
Davide Piffer 2025.08.24 60% relevant
Piffer’s cohort-based design shows that early-life improvements in life expectancy and GDP predict lower completed fertility for those cohorts, providing a development-level mechanism that, when propagated, affects multi‑generation population trajectories central to compounding fertility effects.
The Hereditarian's Gambit, Part 1: Arguing With a Climate Activist Who Won't Have Kids.
Davide Piffer 2025.08.22 60% relevant
By arguing that childbearing choices among climate activists alter the trait mix of future generations, it implicitly relies on compounding demographic effects over time.
The Generational Toll of Abortion
Cremieux 2025.08.20 100% relevant
The piece explicitly models propagation of added births to estimate a total impact larger than the first-order 3–6% increase.
Would Eugenics Work? Simulating Positive Eugenics Targeting IQ
Uncorrelated 2025.07.17 78% relevant
The simulation applies the UN cohort component method and quantitative genetics to show how targeted fertility incentives among higher‑IQ parents propagate across generations, producing multi-decade shifts in national IQ and GDP—an explicit modeling of compounding demographic effects.
Go Ahead And Have Kids
Cremieux 2025.07.12 75% relevant
The preprint’s 'Stabilization' scenario yields a population roughly 90% larger by 2200 than 'Depopulation,' showing long‑run propagation of fertility changes; the paper extends this by linking the larger population to faster innovation and higher GDP per capita.
Cohort fertility projections
Inquisitive Bird 2025.05.27 50% relevant
Accurate, timely estimates of completed cohort fertility are essential for calculating multi‑generation propagation effects; the article’s forward projection method reduces lag and yields a more reliable baseline than period TFR for compounding analyses.
Sub-replacement fertility in pre-baby boom Europe
Inquisitive Bird 2025.02.20 55% relevant
Showing that pre‑WWII Europe reached sub‑replacement fertility implies that, absent the postwar baby boom, compounding cohort effects would have produced large long‑run population shortfalls—exactly the multi‑generation ripple this idea highlights.
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