Using broad historical population estimates, roughly 40% of the world’s population was born before 10 Oct 1952. That estimate comes from comparing the world’s population around late 1952 with cumulative births before that date, and it is only approximate because global birth and death records are incomplete for that era.

Why it’s approximate

World population data for the mid-20th century is usually given as yearly or 5-year estimates, not exact day-by-day counts. The exact share born before 10 Oct 1952 depends on how you interpolate births through 1952 and how you treat mortality, migration, and undercounting in earlier population records.

Practical reading

A reasonable plain-English takeaway is:

  • Not quite half , but a large minority.
  • About 4 in 10 people alive or historically counted by that date had been born before then, under standard global population reconstructions.

Method note

If you want a tighter estimate, the next step is to compute it from a detailed historical birth cohort model rather than from annual population totals alone. That is the only way to move from “roughly 40%” to a more defensible day- specific percentage.

TL;DR: about 40% of the world population had been born before 10 Oct 1952.