Total Fertility Rate

The total fertility rate (TFR) is the average number of children a woman would bear over her reproductive lifetime if she experienced the age-specific fertility rates prevailing during a given period. It is expressed as children per woman and describes current fertility conditions rather than the actual lifetime births of a real group of women.

How it is measured

TFR is a synthetic measure derived from age-specific fertility rates, usually calculated for women aged 15-49 years. These rates relate births to women in successive age groups and are combined across the reproductive span.

• TFR is a period measure because it uses fertility rates observed during a specified period.
• It differs from the crude birth rate, which measures annual births per thousand persons and is affected by the population's age and sex composition.
• It also differs from completed fertility, which records the actual number of children borne by a cohort of women by the end of their reproductive years.

Interpretation and demographic significance

A TFR of about 2.1 children per woman is commonly treated as replacement-level fertility under low-mortality conditions. At this level, a generation of women is approximately replaced by the next generation, but population size need not become stable immediately.

• TFR indicates the overall intensity of childbearing and permits comparisons across populations with different age structures.
• A sustained TFR below replacement level can eventually contribute to population ageing and decline, while a high TFR supports rapid natural increase.
• Population may continue growing after fertility reaches replacement level because of population momentum, especially when a large proportion is entering reproductive ages.
• TFR is a summary measure, not a prediction of how many children each individual woman will actually have.

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