Total Fertility Rate

Total fertility rate (TFR) is among the most commonly used fertility measures. As a period measure, TFR usually examines fertility cross-sectionally. TFR represents the average number of children a woman would have, assuming that current age-specific fertility rates (ASFRs) remain constant throughout her childbearing years (ages 15—49) and she were to survive to the end of her reproductive cycle.

ASFR is calculated by dividing the number of children born to women in an age group by the number of women in that age group. The equation for ASFR is:

where F = fertility, B = births, W = women, x = age at the beginning of the interval, and n = number of years the age interval spans (usually 5-year intervals). TFR builds on ASFR by summing the rates for each age group and multiplying by the length of the age interval:

Another way to measure TFR is through cohort reports of Children Ever Born (CEB). CEB tracks a cohort of women's reproductive histories from the beginning of their childbearing years through completion, resulting in a measure representing the average of all children each woman actually bore. Usually data for AFSR, TFR, and CEB come from surveys or midyear population estimates combined with vital statistics on the number of births. When information about births is collected retrospectively, there is the danger of missing children who died shortly after childbirth.

TFR varies widely throughout the world today and has changed significantly over time. Levels range from well above replacement fertility (TFR = 2.1, an average of two children replacing one's parents, plus a one-tenth factor allowing for under-age-15 child mortality) to below-replacement fertility. In the early 1970s, TFR for the world was 4.5; by 2005, it had fallen to 2.6. For the same periods, in Latin America and the Caribbean, TFR dropped from 5.1 to 2.5. In 2005, Asia, excluding China, had a TFR of 2.8 (it was above 5.0 in the 1970s), with Taiwan and South Korea having among the lowest TFRs in the world at 1.1. European fertility levels were already reaching replacement in the 1970s, but now have dropped significantly below replacement to 1.4. TFR in the United States has remained stable since the 1970s at 2.0. TFR in sub-Saharan Africa has gone from 6.8 to 5.4 during this period; but in 2005, it ranged from a high of 7.9 in Niger to a low of 1.8 in Mauritius. Regional and national TFRs often hide substantial ethnic and racial variation.

Historical changes in TFRs often relate to new contraceptive technologies, access to services, and policies. In China, for example, TFR was close to 6.0 in the early 1970s, prior to the “later-longer-fewer” family planning campaign and the more widely known one-child policy. In 2005, TFR was 1.6; many scholars speculate that this drastic, rapid fertility decline is having significant effects on China's economy, marriage market, and care for the elderly. Changes in fertility across space and time have important [Page 945]context-specific influences on social and demographic processes.