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.     

Is Lowest‐Low Fertility in Europe Explained by the Postponement of Childbearing?

In 2001, more than half of Europe's population lived in countries with a total fertility rate (TFR) at or below 1.3. Use of the adjusted TFR proposed by Bongaarts and Feeney, which takes into account the effects of the ongoing fertility postponement, changes the European fertility map considerably. All 27 countries analyzed had adjusted TFRs in 1995–2000 above 1.4. Thus, the “lowest‐low” fertility in Europe may be interpreted as a temporary consequence of the increasing age at motherhood. However, substantial regional differences in fertility level across Europe persist even when the differential pace of fertility postponement is taken into account. The estimated adjusted TFRs in Europe (1.63) and in the 25‐member European Union (1.71) contrast with the TFR levels of 1.40 and 1.46, respectively. These seemingly small differences have vastly different implications in terms of the potential long‐term pace of population decline.     

Relative cohort size: source of a unifying theory of global fertility transition

Using United Nations estimates of age structure and vital rates for 184 countries at five‐year intervals from 1950 through 1995, this article demonstrates how changes in relative cohort size appear to have affected patterns of fertility across countries since 1950—not just in developed countries, but perhaps even more importantly in developing countries as they pass through the demographic transition. The increase in relative cohort size (defined as the proportion of males aged 15–24 relative to males aged 25–59), which occurs as a result of declining mortality rates among infants, children, and young adults during the demographic transition, appears to act as the mechanism that determines when the fertility portion of the transition begins. As hypothesized by Richard Easterlin, the increasing proportion of young adults generates a downward pressure on young men's relative wages (or on the size of landhold‐ings passed on from parent to child), which in turn causes young adults to accept a tradeoff between family size and material wellbeing, setting in motion a “cascade” or “snowball” effect in which total fertility rates tumble as social norms regarding acceptable family sizes begin to change.     

The End of the Fertility Transition in the Developed World

By the late 1990s the average period total fertility rate in the developed world had declined to 1.6, a level substantially lower than projected in the 1970s and 1980s. This article examines recent trends and patterns in fertility in the developed world with particular emphasis on the effects and implications of changes in the timing of childbearing. The main objective is to demonstrate that while fertility in these countries is indeed low, women's childbearing levels are not as low as period measures such as the total fertility rate suggest. To obtain a full understanding of the various dimensions of fertility change. several indicators are examined, including period and cohort fertility by birth order and childbearing preferences. An analysis of these indicators demonstrates that period fertility measures in many developed countries are temporarily depressed by a rise in the mean age at childbearing. The distortion of the TFR is as great as 0.4 births per woman in Italy and Spain. These effects have been present in many developed countries since the 1970s and could continue for years into the future. But tempo effects are temporary, and once the postponement of childbearing ends—as it eventually must—the corresponding fertility‐depressing effect stops, thus putting upward pressure on period fertility. Countries with very low fertility and substantial tempo effects may well experience rises in fertility in the near future if the timing of childbearing stabilizes. Even if this happens, however, it seems unlikely that fertility will rebound to the replacement level.     

生育进度效应调整指标研究的新进展

随着经济和社会的不断发展,生育推迟现象在全世界范围内日益普遍。由于生育推迟所产生的进度效应会对生育水平造成影响,因此,如何测度生育进度效应便成了人口学界研究的重要内容。自Bongaarts和Feeney的去进度效应总和生育率提出以来,各种新的改进方法与指标不断出现。本文对生育进度效应调整指标的新进展及具体指标进行梳理与比较。从时期角度出发,主要包括方差效应调整后的TFR、PATFR*、调整后的TFRSUV_N和ITFR四种指标;从队列角度出发,主要包括TFRp*、TFR†和ACF三种指标,这些指标有各自的优缺点。研究发现:首先,由于不同去进度效应改进指标的假设、适用条件、研究角度、改进方向都不同,很难有一套数据同时适用于多种去进度方法,因此,生育进度效应的诸多改进指标并没有哪个指标“更好”,只有“更合适”;其次,绝对的去进度效应只能停留在理论层面,而实际上却很难做到,种种去进度方法都只是一种“相对的去”,而不是“绝对的去”。过去我们所熟悉的进度效应是生育推迟,而目前世界范围内生育推迟速度开始逐渐放缓,未来我们甚至不能排除生育推迟在某个时期或某些区域会发生逆转,届时可能会出现与目前影响方向相反的进度效应,这可能是下一步关于生育进度效应研究应该注意的新方向。     

The recent rise in malay fertility: A new trend or a temporary lull in a fertility transition?

Period fertility rates show a recent rise in the fertility of the Malay population of Peninsular Malaysia that became evident in the late 1970s, after more than fifteen years of slow but steady declines. Detailed analysis of age-parity-specific fertility rates suggests that the recent rise is largely due to a “making up” of lower order births (first, second, and third) that had been postponed by a rapid increase in age at marriage. The period trend in higher order births and cohort trends of cumulative fertility from census data point to a continued reduction in completed Malay fertility. Regional analysis shows several states on the east coast with persistent high fertility, although the revolution in marital postponement is national in scope.     

D. V. Glass on the Problems of a Declining Population

During the past quarter century fertility has dropped below replacement levels in many parts of the world. According to United Nations estimates, in 2005 this was the case in 65 countries, comprising 43 percent of the world's population. In many cases, most notably in Europe and East Asia, the shortfall of fertility from the level that would be necessary in the long run to sustain a stationary population is substantial. In Europe, for example, the average total fertility rate for the period 2000–2005 was 1.4. Indefinite maintenance of such a level implies a shrinkage of the total population by one‐third over a generation–roughly every 30 years. Accompanying that rapid decline of total numbers would be an age structure containing a preponderance of the elderly, posing extreme adjustment difficulties for the economic and social system. Societies that wish to avoid radical depopulation would have to engineer a substantial rise infertility–if not to full replacement level (slightly more than two children per woman), then at least to a level that would moderate the tempo of population decline and make population aging easier to cope with. An additional counter to declining numbers, if not significantly to population aging, could come from net immigration. This is the demographic future assumed in the UN medium‐variant projections for countries and regions currently of very low fertility. Thus, for example, in Europe over the period up to 2050 fertility is assumed to rise to 1.85 and net immigration to amount to some 32 million persons. The UN projections also anticipate further improvement in average life expectancy–from its current level of 74 years to 81 years. This factor slows the decline in population size but accelerates population aging. Under these assumptions, Europe's population would decline from its present 728 million to 653 million by 2050. At that time the proportion of the population over age 65 would be 27.6 percent, nearly double its present share. Demographic change of this nature is not a novel prospect. It was envisioned in a number of European countries and in North America, Australia, and New Zealand in the late 1920s and early 1930s. Concern with the possible economic and social consequences generated much discussion at that time among demographers and social scientists at large and also attracted public attention. Possible policy measures that might reverse the downward trend of fertility were also debated, although resulting in only hesitant and largely inconsequential action. The article by D. V. Glass reproduced below is an especially lucid and concise treatment of demographic changes under conditions of low fertility and their economic and social implications. It appeared in Eugenics Review (vol. 29, no. 1, pp. 39–47) in 1937 when the author was 26 years old. Glass's line of argument is broadly representative of the main focus of demographic analysis in the mid‐1930s on aspects of population dynamics, applying the then still novel analytical tool of the stable population model. It also echoes the work of economists then witnessing the great difficulties capitalist economies faced in adjusting to structural changes in consumer demand and labor supply. While Glass addresses these issues primarily with reference to England and Wales, he sees the issues as affecting all industrialized countries. The Malthusian problem of relentless population growth he persuasively declares to be irrelevant for these countries. The Western world faces the opposite problem: population decline, a trend only temporarily masked by the effects of an age distribution that still has a relatively high proportion of women in the child‐bearing ages, reflecting the higher fertility level of the past. A stationary population, Glass cogently argues, is to be welcomed, and he considers the absolute size at which zero growth would be achieved relatively unimportant. In contrast, a continuous population decline would have “thoroughly disastrous” results in an individualist civilization and in “an unplanned economic system.” And, he concedes, somewhat quaintly, that sustained below‐replacement fertility would pose a great problem “even in a country in which the means of production were owned communally.” Glass's conclusions about the reversibility of low fertility are as pessimistic as those of most informed observers today. Still, he sees hope in a future “rationally planned civilization” that would “produce an environment in which high fertility and a high standard of life will both be possible.” In this context, high fertility means the level necessary to sustain the population in a stationary state. By present‐day standards the level Glass calculates as needed for long‐term zero growth is indeed fairly high: 2.87 children per woman. But that figure reflects the fact that, when he wrote, mortality up to age 50 was still fairly high and fertility occurred almost wholly within marriage; it also assumes zero net immigration. In the last 70 years much has changed in each of these three components of population dynamics, both in England and Wales and in the rest of Europe. Still, Glass's commentary remains highly relevant to the discussion of the problems of low fertility today. David Victor Glass (1911–78) was associated with the London School of Economics throughout much of his scientific career. He followed R. R. Kuczynski as reader in demography in 1945 and became professor of sociology in 1948. His work on demography, population history, and population policy had already made him one of the most influential demographers in pre‐World War II Britain. After the war he rose to international prominence through pioneering work on the Royal Commission of Population; through his research on historical demography, the history of demographic thought, and social mobility; and through founding, in 1947, the journal Population Studies, which he edited until his death.     

Low Fertility,Socioeconomic Development,and Gender Equity

While new empirical findings and theoretical frameworks provide insight into the interrelations between socioeconomic development, gender equity, and low fertility, puzzling exceptions and outliers in these findings call for a more all‐encompassing framework to understand the interplay between these processes. We argue that the pace and onset of development are two important factors to be considered when analyzing gender equity and fertility. Within the developed world, “first‐wave developers”—or countries that began socioeconomic development in the nineteenth/early twentieth century—currently have much higher fertility levels than “late developers.” We lay out a novel theoretical approach to explain why this is the case and provide empirical evidence to support our argument. Our approach not only explains historical periods of low fertility but also sheds light on why there exists such large variance in fertility rates among today's developed countries.     

The United Nations on World Population in 2300

The Population Division of the United Nations biennially issues detailed population estimates and projections covering the period 1950–2050. The most recent revision of these estimates and projections, the 2002 assessment, was released in February 2003. At irregular intervals, the Population Division also publishes long‐range projections. The most recent of these, covering the period up to 2150, was issued in 2000, based on the 1998 assessment. On 9 December 2003, the Population Division released the preliminary report on a new set of long‐range projections, dovetailing with the 2002 assessment, that extend over a much longer time span: up to 2300 ( http://www.un.org/esa/population/publications/longrange2/longrange2.htm ). Unlike previous long‐range projections, which, apart from China and In‐dia, were prepared for large regional groupings only, the new projections are elaborated separately for 192 countries. Given the enormous uncertainties of the character of demographic trends over such an extended period, the information content of these projections is somewhat elusive. However, they are expected to be used to provide the demographic input for long‐range models of global climate change. Long‐range population projections also serve to demonstrate the unsustainability of certain seemingly plausible assumptions as to the future course of particular demographic parameters. In the present case, for example, the high‐fertility projection, reflecting a sustained total fertility rate at the relatively modest level of 2.35, by 2300 would yield a population of some 32 billion in the countries now classified as less developed. Or, in a yet more extreme exercise 0/reductio ad absurdum, maintaining constant fertility at present rates would result in a population size of some 120 trillion in the countries now classified as least developed. Apart from the “high fertility” and “constant fertility” models just cited, the projections are calculated for three additional instructive variants: “low fertility,”“medium fertility,” and “zero growth.” Underlying each of the five variants is a single assumption on mortality change: expectation of life at birth creeping up, country‐by‐country, to a 2300 level ranging between 88 and 106 years. International migration is set at zero throughout the period 2050‐2300 in each variant. Thus the projections are unabashedly stylized and surprise‐free, providing a simple demonstration of the consequences, in terms of population size and age structure, of clearly stated assumptions on the future course of demographic variables. Reproduced below is the Executive Summary of the preliminary report on the UN long‐range projections presented to a UN technical working group on long‐range projections at its December 2003 meeting in New York and slightly revised afterward. A full final report on this topic by the Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat will be published later in 2004.     

China's Below‐Replacement Fertility: Recent Trends and Future Prospects

Between 1970 and 1990, China experiencoed a rapid and sharp fertility decline—from total fertility rates of approximately six births to two. The degree to which Chinese fertility has continued to fall after 1990 is controversial. We use survey data from the 1997 National Population and Reproductive Health Survey and from the 2001 Reproductive Health and Family Planning Survey to document recent trends in Chinese fertility. Our estimates provide further evidence that China's fertility is well below‐replacement level at the turn of the twenty‐first century—with TFR levels of approximately 1.5 children per woman. Trends in parity‐specific cohort fertility by age also suggest below replacement completed fertility for cohorts still in the childbearing years. In the article's second section, we identify key components of low period fertility in order to frame our discussion of two questions: 1) in what ways is Chinese low fertility different from/similar to that in other low‐fertility countries? And 2) what are the likely future trends in Chinese fertility?     

Assesssing Cohort Birth Expectations Data from the Current Population Survey, 1971–1981

Data from the fertility supplements to the Current Population Survey from 1971 to 1981 indicate that in the aggregate, the lifetime birth expectations of married women 18 to 39 years old in 1971 will closely approximate their completed cohort fertility. During this period, the youngest group of women, 18 to 24 years old, delayed their childbearing; their short-term expectations (1971–76) were not realized, but they made up enough births in the latter half of the decade to enable them to attain their lifetime birth expectations. In retrospect, the “failure” of birth expectations data to predict the “period” fertility downswing in the 1970s resulted not from poor predictions of married women, but rather from unanticipated marital and subsequent childbearing patterns of women who were single at the beginning of the decade. The authors conclude that birth expectations are useful predictors of completed cohort fertility, if adjustments are made to incorporate changes in the proportions married within the birth cohort.     

Immigration to the UK from High‐Fertility Countries: Intergenerational Adaptation and Fertility Convergence

The fertility of immigrants' children increasingly shapes the ethnic diversity of the population in Western Europe. However, few data are available on the fertility patterns of immigrants and their offspring. This article provides new fertility estimates of immigrants and immigrants' children by ethnic group in the United Kingdom that may provide better‐informed fertility assumptions for future population projection models. The impact of migration‐specific tempo effects on the period TFR of immigrants is analyzed. Among the results, intergenerational fertility transitions strongly contribute both to fertility convergence between ethnic groups and to fertility “assimilation” or “intergenerational adaptation” to the UK mainstream childbearing behavior. Ethnic fertility convergence, particularly marked for populations originating from high‐fertility countries, reflects in part decreasing fertility in sending countries and in part intergenerational adaptation to the UK mainstream. Higher educational enrollment of the daughters of immigrants may partly explain their relatively lower fertility.     

The Limits to Low Fertility: A Biosocial Approach

In light of 30 years of below‐replacement fertility in many industrialized societies, demographers are asking whether fertility could drop even further, or whether there is a “floor” below which it will not fall. A key unanswered question is whether there may be a variable biological component to fertility motivation which ensures that we continue to reproduce. Drawing on evidence from evolutionary biology, ethology, quantitative genetics, developmental psychobiology, and psychology, the article argues that our evolved biological predisposition is toward nurturing behaviors, rather than having children per se. Humans have the unique ability to be aware of such biological predispositions and translate them into conscious, but nevertheless biologically based, fertility motivation. It is likely that we have already reached the limits to low fertility since this “need to nurture,” in conjunction with normative pressures, ensures that the majority of women will want to bear at least one child. A sketch for a biosocial model of fertility motivation is outlined.     

Second Births and the Second Shift: A Research Note on Gender Equity and Fertility

In a set of propositions on fertility transition, Peter McDonald recently proposed that the decline from replacement‐level fertility to low fertility is associated with a combination of high levels of gender equity in individual‐oriented institutions, such as education and market employment, and low levels of gender equity in the family and family‐oriented institutions. Similarly, the “second shift,” or the share of domestic work performed by formally employed women, forms a critical piece of current cross‐national explanations for low fertility. Building on this scholarship, the authors explore whether there is empirical evidence at the individual level for a relationship between gender equity at home, as indicated by the division of housework among working couples with one child, and the transition to a second birth. Results, based on a sample of US couples, indicate a U‐shaped relationship between gender equity and fertility. Both the most modern and the most traditional housework arrangements are positively associated with fertility. This empirical test elaborates the family‐fertility relationship and underscores the need to incorporate family context, including gender equity, into explanations for fertility change.     

Birth month,school graduation,and the timing of births and marriages

We investigated the timing of fertility and marriage in Sweden using exogenous variation in the age at school graduation that results from differences in birth month. Our analysis found that the difference of 11 months in the age at leaving school between women who were born in two consecutive months, December and January, implies a delay in the age at first birth of 4.9 months. This effect of delayed graduation also persists for the timing of second births and first marriages, but it does not affect completed fertility or the overall probability of marriage before age 45. These results suggest the existence of a relatively rigid sequencing of demographic events in early adulthood, and the age at graduation from school emerges as an important factor in determining the timing--but not the quantum--of familyformation. In addition, these effects point to a potentially important influence of social age, defined by an individual's school cohort, instead of biological age. The relevance of social age is likely due to social interactions and peer-group influences exerted by individuals who are in the same school cohort but are not necessarily of the same age.     

The Emergence of Lowest‐Low Fertility in Europe During the 1990s

Lowest‐low fertility, defined as a period total fertility rate at or below 1.3, has rapidly spread in Europe during the 1990s. This article traces the emergence of this new phenomenon to the interaction of five factors. First, tempo and compositional distortions reduce the total fertility rate below the associated level of cohort fertility. Second, socioeconomic changes—including increased returns to human capital and high economic uncertainty in early adulthood—have made late childbearing a rational response for individuals and couples. Third, social interaction effects reinforce this behavioral adjustment and contribute to large and persistent postponement in the mean age at birth. Fourth, institutional settings favor an overall low quantum of fertility. Fifth, postponement–quantum interactions amplify the consequences of this institutional setting when combined with ongoing delays of child‐bearing. The article concludes with speculations about future trends in current and prospective lowest‐low‐fertility countries.     

High Fertility and Children's Schooling in Ghana: Sex Differences in Parental Contributions and Educational Outcomes

This paper explores the linkages at the family level between sustained high fertility and children's schooling in Ghana, in the context of a constrained economic environment and rising school fees. The unique feature of the paper is its exploration of the operational significance of alternative definitions of “sib size” – the number of “same-mother” siblings and “same-father” siblings – in relation to enrolment, grade attainment, and school drop-out for boys and girls of primary and secondary school age. The analysis is based on the first wave of the Ghana Living Standards Measurement Survey (GLSS) data, collected in 1987–88. The results of the statistical analysis lead to the conclusion that the co-existence of high fertility, rising school costs, and economic reversals is having a negative impact on the education of girls, in terms of drop-out rates and grade attainment. Some of the costs of high fertility are borne by older siblings (particularly girls) rather than by parents, with the result that children from larger families experience greater inequality between themselves and their siblings by sex and birth order. Because fathers have more children on average than mothers, the inequality between their children appears to be even greater than between mothers' children, particularly given the importance of fathers' role in the payment of school fees. The paper concludes that the greatest cost for children in Ghana of sustained high fertility is likely to be the reinforcement of traditional sex roles, largely a product of high fertility in the past.     

On the Modernity of Traditional Contraception: Time and the Social Context of Fertility

Many studies of fertility implicitly equate temporal management, biomedical contraception, and “modernity” on the one hand, and “tradition,” the lack of intentional timing, and uncontrolled fertility on the other. This article questions that equation, focusing on the widespread use of periodic abstinence in southern Cameroon. Drawing on field data and the Cameroon Demographic and Health Survey, the article investigates how local concepts of timing shape both contraceptive choice and the evaluation of methods as “modern” or “traditional.” Cameroonian women prefer periodic abstinence because they perceive it as “modern,” a modernity tied both to the social context in which it is taught and to its unique temporal form. By contrast, Depo‐Provera, pills, and the IUD are seen as less‐than‐modern, because they are less exigent of temporal control. The reliance on a behavioral, rather than technological, contraceptive method parallels the experience of the European fertility transition. Cameroonian women draw on a complex social repertoire in making contraceptive choices; methods are preferred or rejected not only on the basis of their efficacy in averting pregnancy, but also because of their correspondence to models of legitimate social action. Reproductive practices may have social motivations that are unrelated to fertility per se.     

Pre‐procreative ages in population stability and cyclicity

Age‐specific models of population renewal (with and without feedback) which imply convergence to a stable state for some levels of fertility or feedback may imply the presence of long‐term cycling around a constant or exponentially changing equilibrium for other levels of fertility or feedback. The switch from one regime to the other is a “bifurcation.”; The conditions for bifurcation involve the roots of an analogue of Lotka's Equation.

Typically bifurcation is induced by raising the strength of feedback or the level of fertility. It has been known since the early 1980s, however, that this is sometimes impossible. It is sometimes impossible even with the linear renewal equation itself and with the most basic of non‐linear models, Lee's cohort feedback model.

Here it is proved that this typical route to bifurcation does not fail for these basic models in the presence of a condition which always holds for realistic applications with higher organisms: the existence of a span of ages before the onset of fertility.

Specifically, a strictly positive lower bound on ages of procreation is proved to be sufficient to guarantee the existence of a rescaling of Lotka's Equation for which the real part of some complex root vanishes. This result holds for absolutely Lebesgue‐integrable (signed) net maternity functions on the positive real line and for absolutely summable (signed) net maternities on the positive integers.

It follows that Coale's rescaling device for the analysis of approach to stability in stable population theory can be implemented for all realistic human net maternity schedules. It also follows that the many special cases of the cohort feedback model throughout population biology will all generate persistent cycling instead of stability if feedback is sufficiently strong.