The U.S. fertility rate has slipped to an estimated 1.57 births per woman in 2025—well below the 2.1 replacement rate—accelerating a demographic shift that threatens to strain federal finances and the social contract. As the population ages, the CBO projects seniors per 100 working-age adults to rise from 24 in 2000 to 43 by mid-century, lifting Social Security and Medicare spending from about 6% of GDP in 2000 to 12.7% in 2055 and widening structural deficits. The challenge is global: two-thirds of the world now lives below replacement fertility, and the IMF sees public debt nearing 100% of world GDP by 2029, with aging dampening growth and lifting pension outlays—most starkly in China. While some hope AI-driven productivity could offset a shrinking workforce, evidence that generous family policies durably raise birthrates is mixed, and proposed pro-natal incentives would take decades to ease fiscal pressures, leaving policymakers to confront hard choices on growth, redistribution and entitlement reform.
Related articles:
Social Security Trustees Report
World Bank: Fertility rate, total (births per woman)
Pew Research Center: Fertility (Topic)
