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.     

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?     

Migration and Intergenerational Replacement in Europe

There are long‐standing concerns over low fertility levels in Europe and an increasingly important debate on the extent to which migration can compensate for below‐replacement fertility. To inform this debate, a wide array of indicators have been developed to assess the joint influence of fertility, mortality, and migration on birth replacement and intergenerational replacement. These indicators are based on various models and assumptions and some are particularly data demanding. In this article we propose a simple method to assess how far migration alters the extent of replacement for a birth cohort as it ages. We term the measure the overall replacement ratio (ORR). It is calculated by taking the size of a female birth cohort at selected ages divided by the average size of the cohorts of mothers in the year of birth. We present estimates of the ORR for a range of European countries representing different replacement regimes. We demonstrate that for many countries net migration has become a key factor in their population trends during the last few decades.     

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.     

Declining world fertility: trends,causes, implications

This Bulletin examines the evidence that the world's fertility has declined in recent years, the factors that appear to have accounted for the decline, and the implications for fertility and population growth rates to the end of the century. On the basis of a compilation of estimates available for all nations of the world, the authors derive estimates which indicate that the world's total fertility rate dropped from 4.6 to 4.1 births per woman between 1968 and 1975, thanks largely to an earlier and more rapid and universal decline in the fertility of less developed countries (LDCs) than had been anticipated. Statistical analysis of available data suggests that the socioeconomic progress made by LDCs in this period was not great enough to account for more than a proportion of the fertility decline and that organized family planning programs were a major contributing factor. The authors' projections, which are compared to similar projections from the World Bank, the United Nations, and the U.S. Bureau of the Census, indicate that, by the year 2000, less than 1/5 of the world's population will be in the "red danger" circle of explosive population growth (2.1% or more annually); most LDCs will be in a phase of fertility decline; and many of them -- along with most now developed countries -- will be at or near replacement level of fertility. The authors warn that "our optimistic prediction is premised upon a big IF -- if (organized) family planning (in LDCs) continues. It remains imperative that all of the developed nations of the world continue their contribution to this program undiminished."     

Policies Addressing the Tempo Effect in Low‐Fertility Countries

The possible negative consequences of current low fertility levels are causing increasing concern, particularly in countries where the total fertility rate is below 1.5. Social inertia and self‐reinforcing processes may make it difficult to return to higher levels once fertility has been very low for some time, creating a possible “low‐fertility trap.” Policies explicitly addressing the fertility‐depressing effect of increases in the mean age at child‐bearing (the tempo effect) may be a way to raise period fertility to somewhat higher levels and help escape the “low‐fertility trap” before it closes. Reforms in the school system may affect the timing of childbearing by lowering the age at completion of education. A more efficient school system, which provides the same qualifications with a younger school‐leaving age, is potentially capable of increasing period fertility and hence exerting a rejuvenating effect on the age composition, even if the levels of cohort fertility remain unchanged. Such policies may also have a positive effect on completed cohort fertility.     

A Cohort Model of Fertility Postponement

We introduce a new formal model in which demographic behavior such as fertility is postponed by differing amounts depending only on cohort membership. The cohort-based model shows the effects of cohort shifts on period fertility measures and provides an accompanying tempo adjustment to determine the period fertility that would have occurred without postponement. Cohort-based postponement spans multiple periods and produces “fertility momentum,” with implications for future fertility rates. We illustrate several methods for model estimation and apply the model to fertility in several countries. We also compare the fit of period-based and cohort-based shift models to the recent Dutch fertility surface, showing how cohort- and period-based postponement can occur simultaneously.     

Stages of the Demographic Transition from a Child's Perspective: Family Size,Cohort Size,and Children's Resources

This article provides a new characterization of stages of the demographic transition from the perspective of children competing for resources within families and cohorts. In Stage 1 falling mortality increases the size of both families and birth cohorts. In Stage 2 falling fertility overtakes falling mortality to reduce family size, but population momentum causes continued growth in cohort size. In Stage 3 falling fertility overtakes population momentum to produce declining cohort size. We apply our framework to census microdata for eight countries and to United Nations population projections for a larger set of countries. The results suggest that most countries spend two to three decades in Stage 2, with declining family size offset by increasing cohort size. From the perspective of children aged 9–11, many countries enter Stage 3 between 2000 and 2010. Other countries, especially in Africa, will continue to experience increasing cohort size for several more decades.     

A demographic explanation for the recent rise in European fertility

Between 1998 and 2008 European countries experienced the first continent-wide increase in the period total fertility rate (TFR) since the 1960s. After discussing period and cohort influences on fertility trends, we examine the role of tempo distortions of period fertility and different methods for removing them. We highlight the usefulness of a new indicator: the tempo- and parity-adjusted total fertility rate (TFRp*). This variant of the adjusted total fertility rate proposed by Bongaarts and Feeney also controls for the parity composition of the female population and provides more stable values than the indicators proposed in the past. Finally, we estimate levels and trends in tempo and parity distribution distortions in selected countries in Europe. Our analysis of period and cohort fertility indicators in the Czech Republic, Netherlands, Spain, and Sweden shows that the new adjusted measure gives a remarkable fit with the completed fertility of women in prime childbearing years in a given period, which suggests that it provides an accurate adjustment for tempo and parity composition distortions. Using an expanded dataset for ten countries, we demonstrate that adjusted fertility as measured by TFRp* remained nearly stable since the late 1990s. This finding implies that the recent upturns in the period TFR in Europe are largely explained by a decline in the pace of fertility postponement. Other tempo-adjusted fertility indicators have not indicated such a large role for the diminishing tempo effect in these TFR upturns. As countries proceed through their postponement transitions, tempo effects will decline further and eventually disappear, thus putting continued upward pressure on period fertility. However, such an upward trend may be obscured for a few years by the effects of economic recession.     

A sensitivity analysis of the bongaarts-feeney method for adjusting bias in observed period total fertility rates

Our sensitivity analysis shows that the adjusted TFR'(t) using the formula of Bongaarts and Feeney (1998), which assumes an invariant shape for the fertility schedule, usually does not differ significantly from an adjusted TFR"(t) that allows the shape of the fertility schedule to change at a constant annual rate. Because annual changes in the shape of the fertility schedules often are approximately constant except in abnormal conditions, the Bongaarts-Feeney (B-F) method is generally robust for producing reasonable estimates of the adjusted TFR'(t). The adjusted TFR'(t) neither represents any real cohort experiences from the past nor forecasts any future trend. It merely provides an improved reading of the period fertility measure, which reduces the tempo distortion.     

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 End of “Lowest‐Low” Fertility?

Total fertility rates fell to previously unseen levels in a large number of countries beginning in the early 1990s. The persistence of TFRs below 1.3 raised the possibility of rapid population aging and decline. We discuss the recent widespread turnaround in so‐called lowest‐low‐fertility countries in Europe and East Asia. The number of countries with TFRs below 1.3 fell from 21 in 2003 to five in 2008. Moreover, the upturn in the TFR was not confined to lowest‐fertility countries, but affected the whole developed world. We explore the demographic explanations for the recent rise in TFRs stemming from fertility timing effects as well as economic, policy, and social factors. Although the current economic downturn may suppress TFRs in the short run, we conclude that formerly lowest‐low‐fertility countries will continue to see increases in fertility as the transitory effects of shifts to later childbearing become less important.     

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.     

Timing effects and the interpretation of period fertility

Low fertility levels and later childbearing in many developed countries have reinvigorated the debate between period and cohort perspectives on fertility and on the meaningfulness of the period total fertility rate (TFR). Here, fertility-timing effects are defined as level changes in period fertility that do not reflect level changes in the completed fertility of cohorts. That definition leads to the average cohort fertility (ACF) as a measure of period fertility adjusted for timing effects. In an influential paper, Bongaarts and Feeney (1998) presented an alternative approach and a different measure, TFR*, to adjust for timing effects. Here, the two measures are compared. In the context of model populations, the ACF performs well, reflecting an average of the fertility of the active cohorts. The Bongaarts-Feeney TFR*, however, is frequently unreliable and can be erratic when there are cycles in period timing. When applied to twentieth-century U.S. experience, the TFR* behaves like a period measure and yields adjustments that are often wide of the mark. The ACF shows the stability associated with cohort measures and quantifies the substantial impact that timing effects had during the "birth dearth" of the 1970s. The period TFR reached a low of 1.74 in 1976, but the ACF never went below 2.06 during the 1970s.     

Cohort Replacement and Homeostasis in World Population, 1950–2100

Using a simple empirical approach, we analyze world and regional‐level cohort replacement as determined by the key components of population dynamics, i.e. fertility, survival, and migration, for 1950–2010, using UN data. We define two kinds of homeostatic relationships among these components: fertility responses to mortality change (type I) and migration responses to changes in net reproduction (type II), and show that both can be observed to some degree in this period. We examine the extent of cohort replacement embodied in the medium‐variant UN population projections over 2010–2100 and consider how the international migration assumptions made in such projections would be affected by a homeostatic perspective.     

Why Is Fertility Lower in Wealthier Countries? The Role of Relaxed Fertility‐Selection

Lower fertility in wealthier countries can be explained in evolutionary terms by three key factors: (i) higher fertility in poorer countries—an evolutionary consequence of many generations of intense “fertility‐selection” favoring innate behaviors promoting high fertility, especially in males; (ii) the empowerment of women in wealthier countries that serves to reduce fertility directly—an evolutionary consequence of selection favoring an inherent preference for lower fertility in females, combined with release from the evolutionary effects of a long history of male control over female fertility; and (iii) offspring access in wealthy countries to public health care, welfare, and other social services, which combined with inherited wealth for offspring, virtually eliminates competition between families for the resource needs of offspring. The combined consequences of (ii) and (iii) mean that the fertility‐selection so prevalent in poor countries is relaxed in wealthy countries, thus allowing random genetic drift to produce an increased relative frequency of innate behaviors promoting low fertility and discontentment with high fertility.     

The Effect of Urbanization on China’s Fertility

The relationship between urbanization and fertility decline is known to be inverse in developed countries. However, the nature of this relationship in developing countries that already have relatively low fertilities is not well-understood. This study aims to illustrate how much urbanization contributed to China’s fertility decline between 1982 and 2008 and forecasts how much it can contribute to future reductions in fertility. The study examines changes in the total fertility rate (TFR) at both the national and provincial levels, given regional differences in the urbanization rate. The results show that changes in rural fertility behavior accounted for most of the decline in the national TFR between 1982 and 2008. This finding suggests that official birth control policies were instrumental in curbing China’s population growth. However, urbanization was responsible for about 22% of the decrease in TFR during this period, and its effect was especially important during the latter years (2001–2008). In most provinces, urbanization associated with a decline in provincial-level fertility. The forecasts indicate that urbanization will become the primary factor behind future declines in national fertility. Given the negative effect of urbanization on the TFR, it is possible to relax the one-child policy without having adverse implications for population growth.     

Fertility decline in Scotland, England and Wales, and Ireland: comparisons from the 1911 census of fertility

Data on family size by year of marriage, age at marriage, and duration of marriage, from the 1911 Fertility Census, are compared between Scotland, England and Wales, Irish county boroughs, and the rest of Ireland. While means show significant inter-country differences, from the 1880s marked similarities are found across all the countries in the pattern of fertility decline, strongly suggesting significant fertility limitation in rural Ireland well before 1911. Noting the implications for the use of rural Ireland as a natural fertility population, the data are instead compared with the Coale-Trussell and Hinde-Woods schedules. The former provides more plausible results, which imply strong period rather than cohort effects in the fertility decline. Except in rural Ireland, little evidence is found for significant fertility limitation early in marriage among younger marrying couples, but many older marrying couples appear to have stopped childbearing at very low parities from an early date.     

Global Demographic Convergence? A Reconsideration of Changing Intercountry Inequality in Fertility

This research challenges the notion that the second half of the twentieth century was a period of global demographic convergence. To be sure, fertility rates fell substantially during the period, but with considerable un‐evenness. The declines in total fertility across population‐weighted countries were sufficiently disproportionate that intercountry fertility inequality, estimated using standard measures of inequality, did not begin to decline until at least 1995. Regression analysis also shows that only very recently did lagging countries begin to catch up with countries that began the transition to low fertility earlier. Contrary to findings on changing intercountry health inequality, sub‐Saharan Africa has had a greater impact on changes in fertility inequality than China. The trend in fertility inequality, where convergence is a relatively new phenomenon, stands in contrast to trends in inequality in other domains, such as income, education, and health.     

Explanations of the fertility crisis in modern societies: A search for commonalities

Near‐global fertility decline began in the 1960s, and from the 1980s an increasing number of European countries and some Asian ones achieved very low fertility (total fertility below 1.5) with little likelihood of completed cohort fertility reaching replacement level. Earlier theory aiming at explaining this phenomenon stressed the incompatibility between post‐industrial society and behaviour necessary for population replacement. Recent theory has been more specific, often concentrating on the current Italian or Spanish situations or on the contrast between them and the situation in either Scandinavia or the English‐speaking countries, or both. Such an approach ignores important evidence, especially that from German‐speaking populations. The models available concentrate on welfare systems and family expenses, omitting circumstances that may be unique to individual countries or longer‐term factors that may be common to all.