totalfertilitet

Totalfertilitet, commonly referred to in English as the total fertility rate (TFR), is the average number of children a woman would bear over her reproductive lifetime if she experienced the current age-specific fertility rates for a given population. It is calculated by summing the age-specific fertility rates across the standard reproductive ages, usually 15–49, typically in five-year age groups (15–19, 20–24, ..., 45–49). The result is expressed as children per woman.

Interpretation and uses: A TFR around 2.1 is often regarded as replacement level in developed countries, where mortality is relatively low; in other settings it may differ due to mortality, sex ratios at birth, and social factors. The TFR is a period measure, reflecting the fertility environment at a point in time, and does not predict the number of children any particular woman will have. For that purpose demographers also study cohort or completed fertility, which follows the actual births of a birth cohort over time.

Applications include cross-country comparisons, tracking fertility transitions, and informing population projections and policy planning. It complements other indicators such as crude birth rate and age-specific fertility rates and is derived from vital statistics records, censuses, and large-scale surveys.

Limitations: The TFR depends on the age structure and current fertility patterns; it is sensitive to data quality and can be affected by underreporting or sampling error. Because it assumes current rates persist, it may not accurately forecast future fertility if behavior or conditions change.