A report on Population decline and Sub-replacement fertility

Only a few countries have had, for the time being, sufficiently sustained sub-replacement fertility (sometimes combined with other population factors like higher emigration than immigration) to have population decline, such as Japan, Germany, Lithuania, and Ukraine.

A reduction over time in a region's population can be caused by sudden adverse events such as outbursts of infectious disease, famine, and war or by long-term trends, for example sub-replacement fertility, persistently low birth rates, high mortality rates, and continued emigration.