Replacement Fertility

Replacement fertility refers to the number of children a woman needs to have, on average, to keep the population stable over time, accounting for factors like mortality and people not having children. In most developed countries, this number is around 2.1 children per woman, meaning each generation replaces itself without growing or shrinking. If fertility drops below this level, the population tends to decline unless offset by immigration; if it rises above, the population may grow. Replacement fertility helps understand how birth rates influence long-term population stability.