Total fertility rate
The number of children who would be born per woman (or per 1,000 women) if she/they were to pass through the childbearing years bearing children according to a current schedule of age-specific fertility rates.
The TFR is calculated as:
TFR = ∑ ASFR a(for single year age groups)
TFR = 5 ∑ ASFR a(for 5-year age groups)
ASFRa = age-specific fertility rate for women in age group a (expressed as a rate per woman).
|Estimate of the average annual TFR for all women aged 15-49, Egypt, 1997-2000.
TFR= 5 (.051 + .196 + .208 + .147 + .075 + .024 +.004) = 3.53
A current schedule of age-specific fertility rates (ASFRs), for one- or five-year age groups
Vital statistics (numerator only), population censuses or population-based surveys
The TFR is the most widely used fertility measure in program impact evaluations for two main reasons: (1) it is unaffected by differences or changes in age-sex composition, and (2) it provides an easily understandable measure of hypothetical completed fertility. TFR includes only live births.
Although derived from the ASFR, a period fertility rate, the TFR is a measure of the anticipated level of completed fertility per woman (or per 1,000 women) if she/ they were to pass through the reproductive years bearing children according to the current schedule of ASFRs. The TFR is only a hypothetical measure of completed fertility, and thus women of reproductive age at any given point in time could have completed family sizes considerably different from that implied by a current TFR, should age-specific fertility rates rise or fall in the future.
Because the TFR is derived from a schedule of ASFRs, the comments and caveats regarding the ASFR also apply to the TFR (i.e., method of computation from different sources of data, effects of changing exposure to pregnancy, and implications of computation for currently married versus all women of reproductive age). As was also the case for the ASFR, the TFR may be computed for women who were continuously married or in union during the reference period of the measure in order to decrease the potentially confounding effects of differences in exposure to the risk of pregnancy (to the extent that differences are associated with marital status). This measure is known as the Total Marital Fertility Rate (TMFR).
Note also that whereas the standard age range for the TFR is ages 15-49, TFRs for other age ranges (e.g., 15- 34) are sometimes used for analytic purposes, for example, in order to decrease the influences of truncation when examining cohort trends from birth history data.