Macroscope
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World wars and the baby boom

Pick a country and switch indicators on: they all line up on one time axis. You can see what changed together, what came first, where official forecasts point and how far past ones missed. Under the chart: observations computed from what is on screen.

Births (since the 1700s)births per year640k 2023
400k600k800k
Births per 1,000 (since the 1700s)births per 1,000 people a year9.7 per 1,000 2023
101520
actual

Without JavaScript you see a ready view: France — Births: long series, Crude birth rate: long series, 1900–1970. Every country has its own page that works without JavaScript (list below); the data is in the API.

How the indicators changed

  • Births (since the 1700s): 833k in 1900 → 850k in 1970 (+2%). Low: 315k in 1916; ×2.7 since then. The trend broke around 1917 and 1923: −27k → +33.2k → +3.38k a year.
  • Births per 1,000 (since the 1700s): 21.6 per 1,000 in 1900 → 16.8 per 1,000 in 1970 (−23%). Peak: 22.4 per 1,000 in 1901; the latest value is 25% lower. The trend broke around 1916: direction reversed (−0.41 → +0.04 a year).

What changed at the same time

  • The fastest rise of "Births (since the 1700s)" was in 1916–1926: 315k → 772k. Over the same years: births per 1,000 (since the 1700s) 9.7 per 1,000 → 19.1 per 1,000.
  • Over the last 10 years (1960–1970): births (since the 1700s) 820k → 850k; births per 1,000 (since the 1700s) 17.9 per 1,000 → 16.8 per 1,000.

How the indicators relate

  • Births (since the 1700s) and births per 1,000 (since the 1700s) (1900–1970, 71 years): levels are strongly related, in the same direction (r = 0.87); year-to-year changes are related too (r = 0.98). Changes line up from year to year too, which is more than a shared trend.

Wars and births

  • World War I (1914–1918). Against the countries not at war in those years (Switzerland, Chile, Denmark, Spain, Iceland and 3 more), net of the pre-war trend: births during the war −44%, 1–5 years after it −1.4%, 6–10 years after +22%.
  • World War II (1939–1945). Against the countries not at war in those years (Switzerland, Chile, Portugal, Sweden), net of the pre-war trend: births during the war −15%, 1–5 years after it +29%, 6–10 years after +38%.
  • War of 1961–1962 on the country's territory (UCDP/PRIO; about 2,360 battle deaths). Against peace-time countries whose fertility was close the year before the war (Finland, Belarus, Austria, Spain, Norway and 5 more), net of each country's pre-war trend: births during the war +3.7%, 1–5 years after it +10%, 6–10 years after +22%; fertility (children per woman) during the war +0.19, 1–5 years after it +0.31, 6–10 years after +0.37.
  • All wars together: of 101 wars on countries' territory since 1955, births 1–5 years after the end were above comparable peace-time countries in 42% of cases (median −1.6%). No significant post-war rise shows up.

Moving together in time does not prove a cause: incomes, cities, education and the era itself act on many indicators at once. These observations suggest where to look, not what causes what.

Key findings

  • UN projection of 2024: in 33 of 42 countries that already report 2024–2025 data, births are below the medium variant; in 8, below the lower bound of the 95% interval.
  • Japan: 709k births in 2024 (including children of foreign nationals). Even the latest official projection (IPSS 2023, medium) expected this level only in 2042, 18 years later. An earlier projection (IPSS 2002, medium) expected it in 2045.
  • Taiwan: 108k births in 2025. Even the latest official projection (NDC 2024, medium) expected this level only in 2036, 11 years later. An earlier projection (NDC 2016, medium) expected it in 2057.
  • China: 7.92M births in 2025. Even the latest official projection (UN WPP 2024, medium) expected this level only in 2050, 25 years later. An earlier projection (UN WPP 2022, medium) expected it in 2054.
  • United States: 1.60 children per woman in 2024. The SSA 2015 projection assumed 2.04 for that year, a gap of −22%.
  • South Korea: 0.80 children per woman in 2025. Projections made before 2020 expected 1.00–1.38 for 2025, while the 2021 and 2023 projections turned out lower than reality: fertility rose slightly in 2024–2025. Errors go both ways.
  • World: 67% of people live in countries with fertility below replacement (2.1), 31% below 1.5. World population is still growing: the UN expects a peak of about 10.3B in 2084.

All forecast-vs-actual checks →

How it works

  • A source for every number. Links go to the primary publication: the statistical office, the UN, the projection archive.
  • Forecast against fact. Next to a figure: what official projections expected for it and how far reality departed.
  • Association is not cause. Moving together in time suggests where to look; the observations under the chart always say so and check a link not only in levels but also in year-to-year changes.
  • Open data. Every table is available as CSV and JSON to check, recompute and reuse.
  • For programs and AI agents. The same data through an API and an MCP server, no page scraping: how to connect.

Data as of 7 October 2026

Country pages

Each country has a page that works without JavaScript: key indicators, observations, past UN and IMF forecasts against actual data, every series with source links. Countries →