Psychology Wiki

Total fertility rate

34,117pages on
this wiki
Revision as of 05:17, September 27, 2012 by Dr Joe Kiff (Talk | contribs)




File:Fertility rate world map 2.png
Map of countries and territories by fertility rate

The total fertility rate (TFR, sometimes also called the fertility rate, period total fertility rate (PTFR) or total period fertility rate (TPFR)) of a population is the average number of children that would be born to a woman over her lifetime if she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime. It is obtained by summing the age-specific rates for a given time-point.

File:Fertility rate.jpg
Graph of Total Fertility Rates vs. GDP per capita of the corresponding country, 2004. Only countries with over 5 Million population were plotted to reduce outlyers. Sources: CIA World Fact Book
The TFR is a synthetic rate, not something that is actually counted. It is not based on the fertility of any real group of women, since this would involve waiting until they had completed childbearing. Nor is it based on counting up the total number of children actually born over their lifetime, but instead is based on the age-specific fertility rates of women in their "child-bearing years," which in conventional international statistical usage is ages 15-44 or 15-49.


An alternative fertility measure is the net reproduction rate (NRR), which measures the number of daughters a woman would have in her lifetime if she were subject to prevailing age-specific fertility and mortality rates in the given year. When the NRR is exactly one then each generation of women is exactly reproducing itself. The NRR is less widely used than the TFR, and the United Nations stopped reporting NRR data for member nations after 1998. But the NRR is particularly relevant where the number of male babies born is very high. The gross reproduction rate (GRR), is the same as the NRR, except that - like the TFR - it ignores life expectancy.


Replacement rates Edit

Replacement fertility is the total fertility rate at which women would have only enough children to replace themselves and their partner. By definition, replacement is only considered to have occurred when the offspring reach 15 years of age. If there were no mortality in the female population until the end of the childbearing years (generally taken as 44 or 49, though some exceptions exist) then the replacement rate would be exactly 2, but in practice it is affected by mortality, especially childhood mortality. The replacement fertility rate is roughly 2.1 births per woman for most industrialized countries but ranges from 2.5 to 3.3 in developing countries because of higher mortality rates.[1] Taken globally, the total fertility rate at replacement is 2.33 children per woman. At this rate, global population growth would trend towards zero.

Developed countries usually have a much lower fertility rate due to greater wealth and education. Mortality rates are low, birth control is understood and easily accessible, and costs are often deemed very high because of education, clothing, feeding, and social amenities. Further, longer periods of time spent getting higher education often mean women have children later in life. The result is the demographic-economic paradox.


The total fertility rate in the United States after World War II peaked at about 3.8 children per woman in the late 1950s and by 1999 was at 2 children. This means that an imaginary woman (defined in the introduction) who fast-forwarded through her life in the late 1950s would have been expected to have about four children, whereas an imaginary woman who fast-forwarded through her life in 1999 would have been expected to have only about two children in her lifetime. The fertility of the population of the United States is below replacement among those native born, and above replacement among immigrant families.[How to reference and link to summary or text] However, the fertility rates of immigrants to the U.S. has been found to decrease sharply in the second generation, correlating with improved education and income. [2]

The lowest TFR recorded anywhere in the world in recorded history is for Xiangyang district of Jiamusi city (Heilongjiang, China) which had a TFR of 0.41. [1] Outside china, the lowest TFR ever recorded was 0.80 for Eastern Germany in 1994.

A population that maintains a TFR of 3.8 over a long time would increase rapidly, whereas a population that maintains a TFR of 2.0 over a long time would decline (unless it had a large enough immigration). The TFR required for a closed population to eventually reach equilibrium in size ranges from 2.5 to 3.3 in developing countries and is near 2.1 in many developed countries (2.075 in the UK for example). However, it may take several generations for a change in the total fertility rate to be reflected in birth rate, because the age distribution must reach equilibrium. For example, a population that has recently dropped below replacement-level fertility will continue to grow, because the recent high fertility produced large numbers of young couples who would now be in their child-bearing years. This phenomenon carries forward for several generations and is called population momentum or population-lag effect. This time-lag effect is of great importance to the growth rates of human populations.



See alsoEdit

External linksEdit

Advertisement | Your ad here

Around Wikia's network

Random Wiki