World population in transition

The world's population growth rate peaked at slightly over 2%/year in the late 1960s and in 1986 is down to 1.7% and falling. Annual numbers added continue to rise because these rates apply to a very large base, 4.9 billion in 1986. According to UN medium variant projections, world population growth will peak at 89 million/year in the late 1990s and then taper off until world population stabilizes in the late decade of the 21st century at about 10.2 billion. Close to 95% of this growth is occurring in less developed countries (LDCs) of Africa, Asia (minus Japan), and Latin America. LDC fertility rates are declining, except in sub-Saharan Africa and parts of Latin America and South Asia, but most have far to go to reach the replacement level of 2.1 births/woman. Fertility is below replacement in virtually all more developed countries. For LDCs, large numbers will be added before stabilization even after attainment of replacement level fertility because of the demographic momentum built into their large and young population bases. This complicates efforts to bridge gaps between living standards in LDCs and industrialized countries. From a new debate about whether rapid population growth deters or stimulates economic growth, a more integrated view has emerged. This view recognizes the complementary relationship between efforts to slow population growth and other development efforts; e.g., to improve health and education, upgrade women's status, increase productivity. Most effective in the increased contraceptive prevalence and fertility declines seen in many LDCs has been the combination of organized programs to increase access to family planning information and supplies with socioeconomic development that enhances the desire for smaller families.     

Our population predicament: a new look

Issued to mark the Population Reference Bureau's 50th anniversary, this issue updates the story of world population presented in its popular predecessor of 1971, "Man's Population Predicament." Estimated at 1/2 billion in 1650, world population reached about 2 billion in 1930, 4 billion in 1975, and is projected to be about 6 billion in 2000. Most of today's rapid growth is occurring among the 3/4 of the world's peoples living in less developed countries where the post-World War II gap between high birth rates and falling death rates has only recently begun to narrow. This growth, coupled with high consumption in developing countries, is putting tremendous pressures on the Earth's resources, environment, and social fabric. New evidence on Europe's population transition and from China, Indonesia, and Thailand in the 1970s suggests that well-designed family planning programs can speed fertility decline but rapid worldwide attainment of replacement level fertility will also require special development efforts and measures that go beyond family planning. Current projections of the world's ultimate peak population range from 8 billion in the mid 21st century to 11 billion in about 2125, depending on when replacement-level fertility is reached. China's drive for a drastic birth rate reduction and the oil crisis might change fertility behavior more rapidly than most demographers have heretofore thought likely.     

Population,projections, and policy: A cautionary perspective

Population projections depend on censuses, vital statistics and sample surveys, all of which have deficiencies that are most marked in the less developed countries (LDCs). Long-range projections by international agencies have recently undergone major revisions, while forecasts of the U.S. population have changed drastically over the past four years. The United Nations typically prepares “high,” “medium” and “low” projections. Even the high projection contains optimistic assumptions about fertility decline, while assumptions of constant or increasing fertility receive no serious attention. The paper suggests that high and constant fertility projections should receive more attention from policy makers, with medium estimates treated more as targets achievable only through considerable programmatic effort. At the same time, economic and social plans should be laid for dealing with the population sizes implied by the “high” variants.     

Planet earth 1984-2034: a demographic vision

In recognition of 1984 as the year of both Orwell's famous futuristic novel and the International Population Conference following up the 1974 World Population Conference, this Bulletin examines the current state of world population and presents the author's speculations on what it might be 50 years from now. World population, now close to 4.8 billion and growing at 1.8%/year, is being shaped by 3 demographic phenomena: prolonged below-replacement fertility in developed nations, perhaps partly in response to the reduced need for workers in the emerging information era; rapid growth despite failing fertility in developing nations, due to earlier rapid mortality decline; and rapid urbanization in developing nations and unprecedented migration from poor to better-off nations. The author's assumptions for nondemographic factors related to population change in the next 50 years are no world war, nuclear or otherwise; global resource adequacy; rapid scientific and technological progress shared equitably; and the demise of capitalism and communism and greatly increased economic aid from advanced to less advanced nations. For 2034 the author envisages nations divided into service/information societies (4% of global population) where immigration balances low fertility to prevent population decline; industrialized nations (38% of total), with fertility close to or at replacement level and growth slowing; developing nations (43%), in sight of replacement level fertility; and least developed nations, with still critical demographic problems but only 15% of the world population. Total population will be 8.03 billion, but growth will be down to 0.8%/year and global zero growth is possible in another 50 years. This relatively optimistic scenario for 2034 will only be possible if mankind acts to see that the stated nondemographic assumptions are borne out.     

Public policy and the total fertility rate: cross-sectional evidence from the LDCs

A framework developed by Easterlin for the analysis of fertility in developing societies is modified and then tested using a sample of 65 less-developed countries. The focus is on assessing the impact of public policy on the national fertility rate. Public policy is reflected in the average levels of education and health in the population and in the condition of the national family planning program. To test for threshold effects with respect to socioeconomic development, the sample is divided on the basis of the infant mortality rate. Fertility rates in those nations characterized by high infant mortality are likely to be determined more by conditions of natural fertility. Those nations with lower infant mortality, and hence greater socioeconomic development, are more likely to exhibit deliberate fertility control. The results of the regression analysis do suggest that different factors influence the national fertility rate depending upon the stage of development. For the least-developed nations, the secondary school enrollment rate, an indicator of the extent of economic mobility, and the ratio of school age children to teachers, a proxy for the national commitment to human capital formation, are important. For the more advanced of the LDCs, adult literacy and the infant mortality rate seem to predominate. For all the developing nations, however, the results confirm the importance of strong family planning programs. The paper concludes with a discussion of the policy implications of the research.     

Declining birth rates and growing populations

Excitement over declining fertility in the Third World needs caution for several reasons. First, it is now too late to solve the world's population problem. Second, the common belief that the birth decline is widespread and is affecting virtually all developing nations goes beyond the data. Third, the notion that birth rates are declining with great speed is not true when the rate is measured against either urbanization or mortality decline. Fourth, a sample of countries indicates that the decline is now slowing rather than accelerating. Fifth, the idea that the declines are due mainly to family planning, and can therefore be assured of continuance in the future, seems unwarranted.Revised version of a paper given at the annual meeting of the American Sociological Association, San Francisco, September 7, 1982.     

Peru's coming baby boomlet

There are grounds for reconsidering the United Nations' population projections for Peru. These projections assume that fertility will continue to decline after 1990 in a smooth and uninterrupted manner, but they ignore several factors related to recovery from the economic and political crises of the 1980s that could significantly alter the pace of decline. The alternative projections we present consider the possibility that Peru's fertility decline will temporarily slow. This alternative hypothesis is conservative in the sense that increases in birth rates are not anticipated, but substantial differences in population size and age structure materialize nonetheless. Moreover, these differences have important implications for future planning in terms of the number of children needing primary health care and education and the number of young adults seeking first-time employment.The authors are grateful to Maryann Belanger, Luis Rosero-Bixby, and Anne Marie Wills for helpful comments, to Wayne Appleton for computer support, and to Terence Kelly for graphics design.     

World population beyond six billion

This world report reviews population growth pre-1900, population change during 1900-50 and 1950-2000, causes and effects of population change and projections to 2050. World population grew from 2 billion in 1900 to almost 6 billion in 2000. Population showed more rapid growth in the 17th and 18th centuries. Better hygiene and public sanitation in the 19th century led to expanded life expectancies and quicker growth, primarily in developed countries. Demographic transition in the 19th and 20th centuries was the result of shifts from high to low mortality and fertility. The pace of change varies with culture, level of economic development, and other factors. Not all countries follow the same path of change. The reproductive revolution in the mid-20th century and modern contraception led to greater individual control of fertility and the potential for rapid fertility decline. Political and cultural barriers that limit access affect the pace of decline. Population change is also affected by migration. Migration has the largest effect on the distribution of population. Bongaarts explains differences in fertility by the proportion in unions, contraceptive prevalence, infertility, and abortion. Educational status has a strong impact on adoption of family planning. Poverty is associated with multiple risks. In 2050, population could reach 10.7 billion or remain low at 7.3 billion.     

Asia's population and development in retrospect and prospect

By 1989 Asia's population will reach 3 billion. That Asia's countries can change the course of population development has been shown by China, whose population growth rate has decreased to 1.2%. 58% of the world's population in 1985 was Asian, and 53% of it was concentrated in 11 Asian countries, of which 37.6% was accounted for by India and China. Asia's population density is 3 times the world average, and the number of persons sustained by a square kilometer of land in Asia is 2.5 times the world average. Asia's population is young (median age 20.3), which means a high dependency burden, a large number of women of childbearing age, and low quality of life, as measured by infant mortality, life expectancy, and literacy. Rapid population growth ensures a low rate of development. Asia's goals are to achieve a 1% growth rate by year 2000, zero population growth and replacement level by 2015 for East Asia and 2020 for South Asia. The World Bank estimates that Asia's population will not stabilize until the end of the 21st century, by which time it will have reached 6 billion. Asia must find a way of achieving both population control and economic development. 5 recommendations are made to the Asian Forum of Parliamentarians on Population and Development (AFPPD): 1) that the AFPPD sponsor the activities of "the Day of 3 billion"; 2) that seminars and conferences on population be held among Asian nations; 3) that high-fertility countries adopt late marriages, few births, and programs for maternal and child health; 4) that organizations for family planning be strengthened and given the resources to upgrade the status of women; and 5) that international cooperation in the area of population be intensified.     

New Cohort Fertility Forecasts for the Developed World: Rises,Falls, and Reversals

With period fertility having risen in many low‐fertility countries, an important emerging question is whether cohort fertility trends are also reversing. We produce new estimates of cohort fertility for 37 developed countries using a new, simple method that avoids the underestimation typical of previous approaches. Consistent with the idea that timing changes were largely responsible for the last decades' low period fertility, we find that family size has remained considerably higher than the period rates of 1.5 in many “low‐fertility” countries, averaging about 1.8 children. Our forecasts suggest that the long‐term decline in cohort fertility is flattening or reversing in many world regions previously characterized by low fertility. We document the marked increase of cohort fertility in the English‐speaking world and in Scandinavia; signs of an upward reversal in many low‐fertility countries, including Japan and Germany; and continued declines in countries such as Taiwan and Portugal. We include in our forecasts estimates of statistical uncertainty and the possible effects of the recent economic recession.     

Low fertility due to delay in -- not dearth of -- births

Population Council demographer John Bongaarts and his colleague Griffith Feeney argue that recent concern about a lack of births overlooks the fact that many women in developed countries are simply choosing to bear children later than women used to. So-called birth dearths are often caused by temporary delays in childbearing. The two demographers have designed a new way for demographers to account for the timing, or tempo, of childbearing in estimates of fertility. Their tempo-adjusted total fertility rate (TFR) allows demographers to correct skewed fertility trends, such as those leading to projections of birth dearths. The new measure provides a better indication of women's true propensity to bear children. Standard measures of fertility are distorted by changes in tempo. Such changes occur when large numbers of couples delay or accelerate their initiation of family building. The authors used historical data and theoretical arguments to validate the tempo-adjusted TFR, which improves upon the two common measures of fertility. Flaws in the TFR and the completed fertility rate (CFR) are corrected by Bongaarts and Feeney's new measure. To demonstrate their new tool, they examined the below-replacement fertility seen in recent decades in the US. By the mid-1990s, the TFR in almost every developed country had fallen below the replacement level of 2.1 births/woman, and in Italy, Spain, and Germany it fell below 1.5. If such fertility persists, declining population size, extreme population aging, and financial pressure upon social security systems may result. However, if fertility preferences hold at current levels, the very low fertility rates observed in the developed world will approach 2 children/couple.     

Data quality and accuracy of United Nations population projections, 1950-95

Between 1951 and 1998, the United Nations (UN) published 16 sets of population projections for the world, its major regions, and countries. This paper reports the accuracy of the projection results. I analyse the quality of the historical data used for the base populations of the projections, and for extrapolating fertility and mortality. I study also the impact this quality has had on the accuracy of the projection results. Results and assumptions for the sets of projections are compared with corresponding estimates from the UN 1998 Revision for total fertility and life expectancy at birth, total population, and the projected age structures. The report covers seven major regions (Africa, Asia, the former USSR, Europe, Northern America, Latin America, and Oceania) and the largest ten countries of the world as of 1998 (China, India, the USA, Indonesia, Brazil, Pakistan, Russia, Japan, Bangladesh, and Nigeria).     

生育率演变的生态学逻辑及人口增长的长期趋势

人口增长的长期过程一直是充满困惑与引发争论的话题,将人类复归到生态系统的普通成员,按照生态学逻辑构建一个由替代生育率内生引导、人口容量外生制约的人口增长新模型,以代替用具体社会经济因子解释短周期人口变动的传统思路,探讨生育率转变的一般模式及人口发展的长期趋势。工业革命以来,全球人口已经或正在经历着第一次、第二次生育率转变,全球生育率演变可以聚类为欧美、亚非拉、撒哈拉以南非洲和东亚四种区域模式;在计划生育政策的推动下,我国在短短的三十年内完整经历了两次生育率转变。极限替代生育率是生育率演变的长期目标,但当前已有一些国家跌破更替水平,这也许会成为各个国家的普遍经历,预示着人口容量约束的日益显性化;世界及主要国家的人口规模正在日益逼近其容量极限,并会在惯性驱动下突破容量限制,达到峰值后再以负增长方式趋近人口容量,同期的生育率也将向极限替代生育率递增复归。按趋势模拟世界和中国的可持续人口容量分别约为65亿人和12亿人。研究设计出测量人口增长惯性的新指标——人口增长惯性系数,它是生育率与实时替代生育率之比或出生率与死亡率之比,相比常用的人口惯性因子更为简便易行。     

Probabilistic Projections of the Total Fertility Rate for All Countries

We describe a Bayesian projection model to produce country-specific projections of the total fertility rate (TFR) for all countries. The model decomposes the evolution of TFR into three phases: pre-transition high fertility, the fertility transition, and post-transition low fertility. The model for the fertility decline builds on the United Nations Population Division’s current deterministic projection methodology, which assumes that fertility will eventually fall below replacement level. It models the decline in TFR as the sum of two logistic functions that depend on the current TFR level, and a random term. A Bayesian hierarchical model is used to project future TFR based on both the country’s TFR history and the pattern of all countries. It is estimated from United Nations estimates of past TFR in all countries using a Markov chain Monte Carlo algorithm. The post-transition low fertility phase is modeled using an autoregressive model, in which long-term TFR projections converge toward and oscillate around replacement level. The method is evaluated using out-of-sample projections for the period since 1980 and the period since 1995, and is found to be well calibrated.     

Baby booms,busts, and population ageing in the developed world

The key challenge facing contemporary society is a process of population ageing rooted mainly in past fertility cycles. The goals of the study reported in this paper were (i) to analyse jointly the post-1930s baby boom and the baby bust that followed, (ii) to consider the specific ways this particular combination influenced the process of ageing in different societies, and (iii) to evaluate some possible implications for policy of different historical experiences. Demographic time series for 27 nations in the developed world were used. The main results confirm the importance of the boom and bust fertility cycle of the second half of the twentieth century for population ageing. Some countries will experience ageing processes driven mainly by the growth of elderly populations while others will age largely as a result of declines in working-age populations. These differences underscore the need to tailor policy priorities for specific patterns of ageing.     

The Projection Problem

While world population has continued to increase, fertility has been falling. Projections out to the year 2050 currently assume that fertility will continue to decline to, or below, replacement. 1) Past projections have been very wrong. Estimates of population growth have alternated between being far too low and far too high. 2) Similarly, public anguish has alternated between extreme fears of over- and under-population, neither supported by eventualities. 3) We do not understand the causes of the current fertility decline and so have little reason to project its continuation. 4) Many of the Asian countries, which are exemplars of the current decline, are exceptional because of coercion and/or vast infusions of Western capital. 5) The population decline may as readily plateau at 3 children as at 2 children. With an unknowable future, an emphasis on future population is misplaced. Concerns should be for the present. Poor families and a stressed environment are struggling with current population levels right now. Complacency about the future is unjustified by the facts and may derail efforts to ensure the continuation of the fertility decline.     

The Role of Relative Cohort Size and Relative Income in the Demographic Transition

This paper summarizes the results of other analyses by the author with regard to the importance of relative cohort size (RCS) in determining male relative income (the income of young adults relative to prime-age workers) and general patterns of economic growth, and in turn influencing fertility in the currently more-developed nations. It then goes on to demonstrate that these same effects appear to have been operating in all of the one hundred-odd nations which have experienced the fertility transition since 1950. Parameter estimates based on the experience of all 189 countries identified by the United Nations between 1950 and 1995 are used to simulate the effects on fertility of migration from Third to First World countries. This exercise suggests that we get the best of all possible outcomes with migration: population is reduced in “overcrowded” Third World nations, total world population growth is substantially reduced, and scores of children are given the opportunity of growing up with all the educational and health advantages of U.S. residents.     

Determinants of national family planning effort

In light of recent research demonstrating a substantial impact of family planning programs on fertility, we develop and estimate a multivariate model of the determinants of national differences in family planning program effort (FPPE). The framework that guides the specification of this model identifies three broad classes of factors—those that create demand for family planning, those that facilitate the initiation and expansion of family planning programs, and finally those that encourage or inhibit program development. The results from multiple regression using 84 less developed countries indicate that demand for family planning, facilitating infrastructure, and certain demographic and geographic factors are important determinants of program effort. These results suggest that popular demand for family planning is helpful, but that policy makers must perceive the adverse consequences of high fertility and have the infrastructure necessary to develop an effective organized family planning program. Current U.S. policies relevant to reducing birth rates are discussed and found to reflect quite well research on determinants of fertility declines among LDCs. U.S. policy also balances the often competing claims of family planners and their opponents by encouraging support to both developmental projects as well as direct aid to family planning program activities.     

The evaluation of China's population policy]

China's population policy has had tremendous effects on the reduction of fertility. The impact of the population policy is manifested in the following aspects. 1) Reducing the size of the total population by 200 million in 17 years. If the population growth rate had remained at its 1970 level of 2.6/1000, the total population would have been 1.28 billion in 1987. 2) The implementation of the population policy accelerated the process of demographic transition. The mortality decline which began in the early 1950s initiated the demographic transition. The Fertility decline began after the birth control policy was implemented and shifted the transition to a low population growth stage even before the socioeconomic conditions which are considered to be the determinants of fertility decline appeared. The fertility decline, in turn, promoted the socioeconomic development of the country. 3) Solving the problem of food; feeding 21.6% of the world's population on 7.1% of the world's farm land is no easy task. The success of population control, no doubt, played an important role in lowering the population growth rate so that the growth of food production could keep pace with the needs of the population. 4) A decline in the dependency ratio is a favorable condition to socioeconomic development. China's dependency ratio of 59.7 is among the lowest in developing countries and is close to the level in developed countries. Therefore, more production output can be used in investment rather than consumption. 5) The fertility decline facilitated a balanced economic growth. The ratio of population growth as compared to the growth of major economic indicators should be considered an important issue in maintaining macroeconomic control. The population policy made it possible for economic growth to surpass population growth.     

The international family planning movement

Over the past 3 decades, the number of women using family planning has increased 6-fold to over 400 million married women of childbearing age. The evolution of behavior and attitudes toward using birth control among third world couples reflects the goals and hard work of an international network of individuals, governments and organizations. This article follows the progression of this movement, from early opposition in developed as well as developing countries, to the present day, when birth control is practiced by a slight majority of the world's women of childbearing age. Among world regions, contraceptive use ranges from about 17% in Africa to 75% in Asia. In some African countries, however, family planning is still a foreign concept, and fewer than 5% of women use any birth control. International organizations played a crucial role in spread of family planning by providing training for developing country professionals, funding actual family planning programs and helping to evaluate programs. But the success of a country's family planning program also was dependent upon a national commitment, and often on a strong socioeconomic setting. The private sector has had a limited role except in some countries, notably in Latin America, but its involvement is likely to expand in the future. Also, as financial support from the US and international organizations wanes, national governments will cover a larger share of the cost. The worldwide increase in the practice of family planning has led to fertility declines in many third world countries, slowing rapid population growth rates. For individuals, family planning has been a liberating influence, allowing them to participate more fully in the shift from traditional to modern society.