The demographic-economic paradox is the inverse correlation found between wealth and fertility within and between nations. This page consists of two tables Table 1 is sourced from the CIA World Factbook''' In Probability theory and Statistics, correlation, (often measured as a correlation coefficient) indicates the strength and direction of a linear The total fertility rate ( TFR, sometimes also called the fertility rate, period total fertility rate (PTFR or total The higher the degree of education and GDP per capita of a human population, subpopulation or social stratum, the fewer childen are born in any industrialized country. Education encompasses both the Teaching and Learning of Knowledge, proper conduct, and technical competency In Biology a population is the collection of inter-breeding organisms of a particular Species; in Sociology In Sociology, social stratification is the hierarchical arrangement of Social classes Castes and strata within a Society. The term 'paradox' comes from the notion that greater means would necessitate the production of more offspring as suggested by the influential Thomas Malthus. Thomas Robert Malthus FRS (13 February 1766 – 23 December 1834 was an English political economist and demographer who expressed views  Roughly speaking, nations or subpopulations with higher GDP per capita are observed to have fewer children, even though a richer population can support more children.
Malthus held that in order to prevent widespread suffering, from famine for example, what he called 'moral restraint' (which included abstinence) was required. Abstinence is a voluntary restraint from indulging a desire or appetite for certain bodily activities that are widely experienced as giving pleasure The demographic-economic paradox suggests that reproductive restraint arises naturally as a consequence of economic progress.
It is hypothesized that the observed trend has come about as a response to increased life expectancy, reduced childhood mortality, improved female literacy and independence, and urbanization that all result from increased GDP per capita, consistent with the demographic transition model. The Demographic transition model (DTM is a model used to explain the process of shift from high Birth rates and high Death rates to low birth rates and low death rates
Before the 19th century demographic transition of the western world, a minority of children would survive to the age of 20, and life expectancies were short even for those who reached adulthood. For example, in the 17th century in York, England 15% of children were still alive at age 15 and only 10% of children survived to age 20. York ( is an historic Walled city sited at the confluence of the rivers Ouse and Foss in North Yorkshire, England. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland 
Birth rates were correspondingly high, resulting in slow population growth. Crude birth rate is the natality or Childbirths per 1000 people per year The agricultural revolution and improvements in hygiene then brought about dramatic reductions in mortality rates in wealthy industrialized countries, initially without affecting birth rates. The British Agricultural Revolution describes a period of development in Britain between the 18th century and the end of the 19th century which saw a massive increase in agricultural Mortality rate is a measure of the number of Deaths (in general or due to a specific cause in some population scaled to the size of that population per unit time In the 20th century, birth rates of industrialized countries began to fall, as societies became accustomed to the higher probability that their children would survive them. Cultural value changes were also contributors, as urbanization and female employment rose.
Since wealth is what drives this demographic transition, it follows that nations that lag behind in wealth also lag behind in this demographic transition. The developing world's equivalent Green Revolution did not begin until the mid-twentieth century. The Green Revolution refers to the transformation of Agriculture that began in 1945 at the request of the Mexican government to establish an agricultural research station to This creates the existing spread in fertility rates as a function of GDP per capita.
Another contributor to the demographic-economic paradox may be religion. Religious societies tend to have higher birth rates than secular ones, and richer, more educated nations tend to advance secularization.  This may help explain the Israeli and Saudi Arabian exceptions, the two notable outliers in the graph of fertility versus GDP per capita at the top of this article. For a topic outline on this subject see List of basic Israel topics. The Kingdom of Saudi Arabia, KSA ( المملكة العربية السعودية, al-Mamlaka al-ʻArabiyya as-Suʻūdiyya) or Suudi In American media it is widely believed that America is also an exception to global trends. The current fertility rate in America is 2. 09, higher than in most other developed countries.  This may be due to the United States having a high percentage of religious followers compared to Europe as a whole. 
The role of different religions in determining family size is complex. For example, the Catholic countries of southern Europe traditionally had a much higher fertility rate than was the case in Protestant northern Europe. However, economic growth in Spain, Italy, etc, has been accompanied by a particularly sharp fall in the fertility rate, to a level below that of the Protestant north. Spain () or the Kingdom of Spain (Reino de España is a country located mostly in southwestern Europe on the Iberian Peninsula. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest This suggests that the demographic-economic paradox applies more strongly in Catholic countries, although Catholic fertility started to fall when the liberalizing reforms of Vatican II were implemented. The Second Ecumenical Council of the Vatican, or Vatican II, was the twentieth century Ecumenical Council of the Roman Catholic Church. It remains to be seen if the fertility rate among (mostly Catholic) Hispanics in the U. S. will follow a similar pattern.
Another possible explanation for the "American exception" is its much higher rate of teenage pregnancies, particularly in the southern US, compared to other countries with effective sexual education; this does not contradict the religious-beliefs hypothesis. Teenage pregnancy is defined as a Teenage or underage girl usually within the ages of 13-17 becoming pregnant
In his book America Alone: The End of the World as We Know It, Mark Steyn asserts that the United States has higher fertility rates because of its greater economic freedom compared to other industrialized countries. America Alone The End of the World as We Know It (ISBN 0-89526-078-6 is a New York Times bestselling nonfiction book by Mark Steyn, published Mark Steyn, born in Canada in 1959, is a self-described conservative writer and commentator about politics arts and culture Economic freedom is freedom to produce trade and consume any goods and services acquired without the use of force fraud or theft However, the countries with the highest assessed economic freedom, Hong Kong and Singapore, have significantly lower birthrates than the United States. According to the Index of Economic Freedom, Hong Kong is the most economically free country in the world. Hong Kong also has the world's lowest birth rate. However, studies have also suggested a correlation between population density and fertility rate.  Hong Kong and Singapore have the third and fourth-highest population densities in the world. List of countries and dependencies by Population density in inhabitants/km² This may account for their very low birth rates despite high economic freedom. By contrast, the United States ranks 180 out of 241 countries and dependencies by population density.
A reduction in fertility can lead to an ageing population which leads to a variety of problems, see for example the Demographics of Japan. As of June 2008 Japan 's Population is around 1277 million making it the world's tenth most populated country
A related concern is that high birth rates tend to place a greater burden of child rearing and education on populations already struggling with poverty. Consequently, inequality lowers average education and hampers economic growth. In Mathematics, an inequality is a statement about the relative size or order of two objects or about whether they are the same or not (See also equality  Also, in countries with a high burden of this kind, a reduction in fertility can drive economic growth as well as the other way around.