Sub-replacement fertility

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation being less populous than the older, previous one in a given area. In developed countries sub-replacement fertility is any rate below approximately 2.1 children born per woman, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates.[1] Taken globally, the total fertility rate at replacement was 2.33 children per woman in 2003.[1] This can be "translated" as 2 children per woman to replace the parents, plus a "third of a child" to make up for the higher probability of boys being born and early mortality prior to the end of their fertile life.[2]

Replacement level fertility in terms of the net reproduction rate (NRR) is exactly one, because the NRR takes both mortality rates and sex ratios at birth into account.

Map of countries by fertility rate (2015)
  7–8 Children
  6–7 Children
  5–6 Children
  4–5 Children
  3–4 Children
  2–3 Children
  1–2 Children

As of 2010, about 48% (3.3 billion people) of the world population lives in nations with sub-replacement fertility.[3] Nonetheless most of these countries still have growing populations due to immigration, population momentum and increase of the life expectancy. This includes most nations of Europe, Canada, Australia, Brazil, Russia, Iran, Tunisia, China, the United States and many others. The countries or areas that have the lowest fertility are in developed parts of East and Southeast Asia: Singapore, Macau, Taiwan, Hong Kong and South Korea.[4] Only a few countries have had, for the time being, sufficiently sustained sub-replacement fertility (sometimes combined with other population factors like higher emigration than immigration) to have population decline, such as Japan, Germany, Lithuania, and Ukraine.


Further information: Fertility factor (demography)

There have been a number of explanations for the general decline in fertility rates in much of the world, and the true explanation is almost certainly a combination of different factors.

Higher education[edit]

The fact that more people are going to colleges and universities, and are working to obtain more post-graduate degrees there, along with the soaring costs of education, have contributed greatly to postponing marriage in many cases, and bearing children at all, or fewer numbers of children. And the fact that the number of women getting higher education has increased has contributed to fewer of them getting married younger, if at all. In the US, for example, females make up more than half of all college students, which is a reversal from a few decades back.[7]

Economic development[edit]

Further information: Income and fertility

The growth of wealth and human development are related to sub-replacement fertility. High costs of living and job insecurity can make it difficult for young people to marry and start families.

In Eastern European countries, the fall of communism has led to an economic collapse in many of these countries in the 1990s. Some countries, such as those which experienced violent conflicts in the 1990s, were very badly affected. Large numbers of people lost their jobs, and massive unemployment, lack of jobs outside the big cities, and economic uncertainty discourages people from having children.[8]


The increase of urbanization around the world is considered by some a central cause. In recent times, residents of urban areas tend to have fewer children than people in rural areas.[9][10] The need for extra labour from children on farms does not apply to urban-dwellers. Cities tend to have higher property prices, making a large family more expensive, especially in those societies where each child is now expected to have their own bedroom, rather than sharing with siblings as was the case until recently. Rural areas also tend to be more conservative with less contraception and abortion than urban areas.


Changes in contraception are also an important cause, and one that has seen dramatic changes in the last few generations. Legalization and widespread acceptance of contraception in the developed world is a large factor in decreased fertility levels; however, for instance in a European context where its prevalence has always been very high in the modern era, the fertility rates do not seem to be influenced significantly by availability of contraception.[11]

Assisted reproductive technology[edit]

The availability of assisted reproductive technology (ART) may foster delay of childbearing because many couples are inclined to think that it will solve any fertility problems they might encounter in the future.[11] Its effect on total fertility rate is extremely small but government support for it is beneficial for families.[11]

Government policies[edit]

In the 1970s the Singaporean government encouraged small families.

Some governments have launched programmes to reduce fertility rates and curb population growth. Notably, China implemented a one-child policy for 35 years.

Although today Singapore has a very low fertility rate, and the government encourages parents to have more children because birth rates have fallen below the replacement rate, in the 1970s the situation was the opposite: the government wished to slow and reverse the boom in births that started after World War II (see the poster).


It has been shown, both historically and in the present day, that societies engaged in a prolonged state of war experience a substantial lag in fertility rate. The most notable examples of this phenomenon are widely accredited to the First and Second World Wars. Modeled by these examples, "total war" subjects individuals to intense social upheavals and a heavy psychological impact that forcefully prioritizes survival and economic stability over the need to reproduce for the duration of the conflict. Events like these subsequently pave way for an active effort to repopulate, such as the "baby boom" after the Second World War.[12]

Tempo effect[edit]

The conventionally reported measure of TFR, the period TFR (based on the level of fertility or number of births in a given year), is affected by a statistical effect called the tempo effect which makes it a misleading measure of overall (life cycle) fertility.

Specifically, if the age of childbearing increases – assuming that the total number of births over a life cycle remains unchanged – the measured TFR is lower (the births happen in a later year), but when the age of childbearing stops increasing the TFR increase, due to these births catching up. For illustration, if women in the past always had 1 child at the age of 20 (TFR of 1), and all women born in 1980 or later postponed having children until age 30 in the year 2000, there would be no births for 10 years (TFR of 0). After 10 years (assuming flat population structure, no deaths, etc.), in 2010, it would suddenly jump back up (TFR of 1), even though the life cycle TFR was always 1.

Thus, period TFR reflects not only life cycle TFR, but also timing effects, and these effects are conflated in a simple period TFR number. Life cycle TFR is unambiguous, and strict measure of life cycle fertility are not affected by this effect (e.g., counting the average children that have been born to all women who cease child-bearing in a given year via menopause, sterilization, death, etc.), but are lagging statistics because they require women to cease child-bearing before they are counted. Thus, adjusted measures of TFR – period TFR, adjusted for timing – are proposed instead to give a more accurate measure of life cycle fertility, without needing to wait until women have definitively ceased bearing children.

Thus, if age of childbearing is increasing and life cycle fertility is decreasing, period TFR will initially overstate the decline, and then may have a spurious increase even if life cycle fertility is actually still declining. For instance, this is computed to be the case in Spain in the period 1980–2002.[13]

John Bongaarts and Griffith Feeney have suggested that this tempo effect is driving the decline of measured fertility rate in the developed world.[14] Taking tempo changes into account, adjusted birth rates for a number of European countries are higher than the conventional TFR.[15] A particularly strong example is the Czech Republic in the period 1992–2002, which witnessed a steady rise in childbearing age. Hence, the period TFR dropped sharply, overstating the decline in life cycle fertility.[13]

Partnership instability[edit]

Also, a number of sociologists and demographers have pointed out that among those who co-habit, without marrying, are now usually likely to have fewer children than those who are married, due to the lack of commitment in the male/female relationship. This uncertainty induces a 'wait and see' approach in many cases, especially on the part of the female.[16] A study came to the result that individual decisions arising from the instability of modern partnerships are a major cause of European sub-replacement fertility.[11]

Frequency of sex[edit]

Another explanation for falling fertility could be a reduction in the frequency of sex. For example, according to a survey published by the Japanese Family Planning Association in March 2007, a record 39.7 per cent of Japanese citizens aged 16–49 had not had sex for more than a month.[17]

Social and government acceptance of non-traditional families[edit]

In recent years, the marriage rate in many countries (especially in the West) has decreased.[18] As more young people reject traditional lifestyles that include marriage, the issue arises whether the state accepts non-traditional families such as those based on non-marital cohabitation, or whether it actively discourages non-marital childbearing. In Western countries, the former position of accepting cohabiting couples and supporting them as a legitimate form of family has been connected with a higher fertility rate (eg. Scandinavian countries, France, where most births occur outside of marriage[19]) while the latter (such as East Asia - Japan , Hong Kong, Taiwan, Singapore) has been connected with a very low fertility rate.[20]

High investment per child[edit]

People are more likely in modern society to invest strongly in the needs of their children, such as offering them the best education, shelter (a room only for the child), travel, cultural activities etc. In the past, when child mortality was high, people had more children, but invested less in them; today as parents usually no longer experience incertitude at the birth of child whether the child will live to adulthood or not, they are more likely to strongly invest in that child. But strongly investing in each child makes it more difficult to have large numbers of children; this being a "quantity vs.quality trade-off" effect.[21]

Gender expectations and norms[edit]

Social norms both within the family and in society at large determine fertility levels. The quality of couple relations in terms of support given to the woman matters, with studies on fertility in the West showing a U-shaped relationship between gender equity within the couple and fertility: in countries with very low fertility rates, the probability of a woman to have the second child occurs at the extremes - either very low gender equality or very high gender equality. [22] This is also reflected at a social level: countries which are neither sufficiently patriarchal to coerce women into having large families against their will, nor sufficiently egalitarian to incentivize women to have more children through strong support (such as subsidized childcare and good support of working mothers), have very low fertility rates, especially among educated women. Where women are expected to 'choose' between their professional and public life, or having children, the more educated the woman is, the more likely she is to choose the former. The strong emphases on the domestic role of women in Germany (unlike Scandinavia and France) was described as the cause of the very low fertility in that country.[23][24][25]

Historical effects[edit]

The Greek historian Polybius largely blamed the decline of the Hellenistic world on low fertility rates,[26] writing his work The Histories that:

In a speech to Roman nobles, the Emperor Augustus commented on the low birthrates of the Roman elite:[28]

Upon the establishment of the Roman Empire, Emperor Augustus would introduce legislation to increase the birthrates of the Roman nobility.[30]

Some believe that not only the Great Recession, but the Great Depression, may have been the result of a decline in birthrates overall. Clarence L. Barber, an economist at the University of Manitoba, pointed out how demand for housing in the US, for example, began to decline in 1926, due to a decline in 'household formation' (marriage), due, he believed, to the effects of World War I upon society. In early 1929, US housing demand declined precipitously. And, of course, the stock market crash followed in October of that same year.[31]

Even though the overall world population continues to increase, it is more at the 'back end' than the 'front end' that this is occurring. That is, more people are kept alive than in the past due to improved nutrition, more refrigeration and better sanitation worldwide, as well as health care advances, from vaccines to antibiotics, and many other advances in medications and in different improvements in health care. Certainly, in advanced nations, few groups would be considered to be "breeding like rabbits". The 'baby boom' (1946–1964) in the US, was likely, if Barber's contentions are correct, more of a return to birthrates closer to historical norms, like those of the first decade of the 20th century (but the 'baby boom' of 1946–1964 were still lower than the 1900–1910 period), with birth dearths both before and since making the so-called "baby boom" appear so big.

Attempts to forcefully increase the fertility rate[edit]

One of the most notorious policies of forceful attempts to increase the TFR is that which occurred in communist Romania in the period of 1967-1990 during communist leader Nicolae Ceaușescu, who adopted a very aggressive natalist policy which included outlawing abortion and contraception, routine pregnancy tests for women, taxes on childlessness, and legal discrimination against childless people. This period has later been been depicted in movies and documentaries (such as 4 Months, 3 Weeks and 2 Days, Children of the Decree). These policies temporarily increased birth rates for a few years, but this was followed by a later decline due to an increased use of illegal abortion.[32][33] Ceaușescu's policy resulted in over 9,000 women who died due to illegal abortions,[34] large numbers of children put into orphanages by parents who couldn't cope with raising them, street children in the 1990s (when many orphanages were closed and the children ended on the streets), and overcrowding in homes and schools. In addition, Ceaușescu's demographic policies are feared of having very serious effects in the future, because the generations born under Ceaușescu are large (especially the late 1960s and the 1970s), while those born in the 1990s and 2000s are very small. This is believed to cause a very serious demographic shock when the former generations retire, as there will not be sufficient young people to form the workforce and support the elderly.[35][36][37] Apart from Romania, a relatively similar policy of restricted reproductive rights during that period also existed in Communist Albania, under Enver Hoxha (see Abortion in Albania).

Current effects[edit]

Population aging may pose an economic challenge to governments as the number of retired citizens drawing public pensions rises in relation to the number of workers. This has been raised as a political issue in France, Germany, and the United States where many people have advocated policy changes to encourage higher birth and immigration rates.

Analysing data for 40 countries, Lee et al. show that fertility well above replacement and population growth would typically be most beneficial for government budgets. However, fertility near replacement and population stability would be most beneficial for standards of living when the analysis includes the effects of age structure on families as well as governments. And fertility moderately below replacement and population decline would maximize standards of living when the cost of providing capital for a growing labour force is taken into account.[38]


United Nation's population projections by location.
Note the vertical axis is logarithmic and represents millions of people.

Sub-replacement fertility does not immediately translate into a population decline because of population momentum: recently high fertility rates produce a disproportionately young population, and younger populations have higher birth rates. This is why some nations with sub-replacement fertility still have a growing population, because a relatively large fraction of their population are still of child-bearing age. But if the fertility trend is sustained (and not compensated by immigration), it results in population ageing and population decline. This is already happening and impacts first most of the countries of Europe and East Asia.

Current estimates expect the world's total fertility rate to fall below replacement levels by 2050,[39] although population momentum will continue to increase global population for several generations beyond that. The development of the world population is linked with concerns of overpopulation, sustainability and exceeding Earth's carrying capacity.

Some governments, fearful of a future pensions crisis, have developed natalist policies to attempt to encourage more women to have children. Measures include increasing tax allowances for working parents, improving child-care provision, reducing working hours/weekend working in female-dominated professions such as healthcare and a stricter enforcement of anti-discrimination measures to prevent professional women's promotion prospects being hindered when they take time off work to care for children. Over recent years, the fertility rate has increased to around 2.0 in France and 1.9 in Britain and some other northern European countries, but the role of population policies in these trends is debated.[40]

European analysts hope, with the help of government incentives and large-scale change towards family-friendly policies, to stall the population decline and reverse it by around 2030, expecting that most of Europe will have a slight natural increase by then. C. D. Howe Institute, for example, tries to demonstrate that immigration can not be used to effectively counter population ageing.[41]

Cases of fertility rate increases in individual countries[edit]

United States[edit]

While much of the world has experienced declining fertility rates over the last twenty years, the total fertility rate in the United States has remained relatively stable in comparison.[42] This is largely due to the high fertility rate among communities such as Hispanics, but it is also because the fertility rate among non-Hispanic whites in the US, after falling to about 1.6 in the 1970s and early 1980s, had increased and is now around 1.89 rather than lower to the 1.6 level common in Europe. It can also be explained by substantial immigration.

New England has a rate similar to most Western European countries, while the South, Midwest, and border states have fertility rates considerably higher than replacement. States where The Church of Jesus Christ of Latter-day Saints has a strong presence, most notably Utah, also have higher-than-replacement fertility rates, especially among the LDS population. Heaton and Goodman (1985) found that LDS women average about one child more than women in other religious groups.[43]

Other developed countries[edit]

Some other developed countries are experiencing an increase in their birth rate, including France, which recorded a TFR of over 2.00 in 2008;[44] the United Kingdom where TFR increased from 1.64 in 2000 to 1.98 in 2010;[45][46] Australia, where the birth rate rose from 1.73 in 2001[47] to 1.93 in 2007[48] and New Zealand, where the TFR was 2.2 in 2008.[49]

Israel is the only developed country that has never had sub-replacement fertility; a declining Arab and Bedouin fertility rate is countered by religious Jewish groups (mostly Haredim) with higher than average fertility rates. In addition, the (mostly non-religious)[citation needed] aliyah Jews from the former USSR shifted from a 1 child per woman fertility rate to an average fertility rate close to 2.2 children per woman. As of 2008, Israel's Jewish fertility rate is the highest among the industrial nations.[50]

See also[edit]

Economic dynamics


  1. ^ a b Espenshade TJ, Guzman JC, Westoff CF (2003). "The surprising global variation in replacement fertility". Population Research and Policy Review. 22 (5/6): 575. doi:10.1023/B:POPU.0000020882.29684.8e. , Introduction and Table 1, p. 580
  2. ^ For example in the United Kingdom in 2001 304,635 boys were born as opposed to 289,999 girls, and some of these girls will not survive to the end of their child bearing years. In future, therefore, the girls born in this year would have to have more than two children each to replace the total population. For a full explanation see 'Replacement Fertility, What has it been and What does it mean?' (PDF)
  3. ^ "Figure 8: Population by Total Fertility (millions)" in World Population Prospects, the 2010 Revision. United Nations, Department of Economic and Social Affairs, Population Division (2011)
  4. ^
  5. ^ "Field Listing: Total Fertility Rate". The World Factbook. Retrieved 2016-04-24. 
  6. ^ "Country Comparison: GDP - Per Capita (PPP)". The World Factbook. Retrieved 2016-04-24. 
  7. ^ Mother's Educational Level Influences Birth Rate
  8. ^
  9. ^ "[Analysis of factors related to the recent decline in birth rate in Japan]". Nihon Koshu Eisei Zasshi. 42 (2): 121–8. February 1995. PMID 7718907. 
  10. ^ "Factors affecting the most recent fertility rates in urban-rural Bangladesh". Soc Sci Med. 44 (3): 279–89. February 1997. doi:10.1016/s0277-9536(96)00076-7. PMID 9004364. 
  11. ^ a b c d Eshre Capri Workshop, G. (2010). "Europe the continent with the lowest fertility". Human Reproduction Update. 16 (6): 590–602. doi:10.1093/humupd/dmq023. PMID 20603286. 
  12. ^ Caldwell, John C. (2007-09-21). Demographic Transition Theory. Springer Science & Business Media. ISBN 9781402044984. 
  13. ^ a b Tempo Effect and Adjusted TFR
  14. ^ Bongaarts, J. (2002). "The End of the Fertility Transition in the Developed World". Population and Development Review. 28 (3): 419. doi:10.1111/j.1728-4457.2002.00419.x. 
  15. ^ European Demographic Data Sheet 2008
  16. ^ Fertility Differences between Married and Cohabiting Couples: A Switching Regression Analysis
  17. ^ [1]
  18. ^
  19. ^
  20. ^
  21. ^
  22. ^
  23. ^
  24. ^
  25. ^
  26. ^ "Polybius, Histories, book 37, Depopulation of Greece". Retrieved 2016-02-18. 
  27. ^ Polybius (2012). The Histories of Polybius: Translated from the Text of F. Hultsch. Cambridge University Press. p. 510. ISBN 1-1080-5079-4. Retrieved November 2, 2013. 
  28. ^ "Projekt Gutenberg". Project Gutenberg. Retrieved 2016-02-18. 
  29. ^ Dio, Cassius (2004). Dio's Rome. 4. Kessinger Publishing. p. 86. ISBN 1-4191-1611-8. Retrieved 3 November 2013. 
  30. ^ "Ancient Rome: Administration of Rome and Italy". Encyclopædia Britannica Online. Encyclopædia Britannica, Inc. Retrieved January 17, 2015. 
  31. ^ [2]. Real gross housing expenditures on new units can be separated into two multiplicative components; housing starts and the real average investment per unit. 25 After estimating the determinants of each, Bolch, Fels, and McMahon examined the building hypothesis by simulating what would have been the case in each situation if a "normal" situation had occurred. 26 The result was overbuilding in the number of housing units from 1922 through 1929. They also found "overinvestment" per individual housing unit from 1921 to 1928 and conclude that excessive housing starts relative to family formation led to the sharp decline in housing construction at the end of the twenties. In their view the demographic changes in the twenties were the proximate causes of this. In a 1978 study Clarence Barber was even more emphatic on the importance of demographic changes, suggesting that these were the ultimate explanation of the Great Depression. 27 Basing his explanation on a Harrod-Domar growth model, Barber argues that the rapid decline in the population's growth rate disturbed that equilibrium, and this rapid fall in the natural growth rate initiated the depression
  32. ^
  33. ^
  34. ^ Kligman, Gail. "Political Demography: The Banning of Abortion in Ceausescu's Romania". In Ginsburg, Faye D.; Rapp, Rayna, eds. Conceiving the New World Order: The Global Politics of Reproduction. Berkeley, CA: University of California Press, 1995 :234-255. Unique Identifier : AIDSLINE KIE/49442.
  35. ^
  36. ^
  37. ^
  38. ^ Lee, Ronald; Mason, Andrew; members of the NTA Network (10 October 2014). "Is Low Fertility Really a Problem? Population Aging, Dependency, and Consumption". Science. 346 (6206): 229–234. doi:10.1126/science.1250542. 
  39. ^ "population trends (dynamically generated)". EarthTrends. World Resources Institute. Retrieved 13 June 2010. 
  40. ^ Suddenly, the old world looks younger. The Economist, 14 June 2007.
  41. ^ Guillemette, Yvan and Robson, William B.P. (September 2006) No Elixir of Youth: Immigration Cannot Keep Canada Young. C.D. Howe Institute
  42. ^ Total Fertility Rate of the United States, History plus Forecast, International Futures, retrieved 26 April 2012 
  43. ^ Goodman, Kristen L.; Heaton, Tim B. (1985). "Religion and Family Formation". Review of Religious Research. 26 (4): 343–359. JSTOR 3511049. 
  44. ^ Tabc3 Tableau complémentaire 3 : Taux de fécondité par groupe d'âges.
  45. ^ Doughty, Steve (17 September 2012) British birth rate has soared to one of highest in Europe thanks to increase in migrants. Daily Mail
  46. ^ "Births and Deaths in England and Wales, 2011 (Provisional)". Office for National Statistics. Retrieved 13 January 2013. 
  48. ^ "3301.0 – Births, Australia, 2007, Australian Bureau of Statistics". Australian Bureau of Statistics. 
  49. ^ Collins, Simon (19 February 2009). "Baby boom goes against mothers' advice". The New Zealand Herald. Retrieved 14 November 2011. 
  50. ^ "Demographic Optimism, Not Pessimism -Yoram Ettinger". January 2013. 

External links[edit]