Subreplacement

Origin

- + replacement

Full definition of subreplacement

Adjective

1. (demography, of a birth rate) Below the level needed to maintain the current population.
• 2011, James W. White, Mirrors of Memory: Culture, Politics, and Time in Paris and Tokyo, University of Virginia Press (2011), ISBN 9780813930701, page 219:The other is the fact that the population of Japan has begun to shrink, the result of years of subreplacement birth rates.