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.     

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.     

Birth delays skew developing world's fertility figures

This article explains that birth delays skew developing world's fertility figures. When successive groups of women who have delayed childbearing start having children, the rapid fertility decline stalls. Such change in the timing of childbearing skews the total fertility rate (TFR). Analysis of the tempo component of TFR trends in Taiwan suggests that tempo effects reduced its TFR by about 10% in the late 1970s and early 1990s and by about 19% in the late 1980s. In Colombia, on the basis of increasing mean maternal age at childbirth between the 1970s and the late 1980s, tempo distortions of the TFR during the most of the 1980s seem likely. Moreover, many developing countries are now experiencing rapid fertility declines that are in part attributable to tempo changes. These changes have accelerated past fertility transitions, but they also make these countries vulnerable to future stalls in fertility when the delays in childbearing end. Since fertility reductions caused by tempo effects lead to real declines in birth rates and hence in population growth, countries that wish to reduce birth rates can take actions that encourage women to delay marriage and the onset of childbearing.     

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TFR_SUVN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,...     

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.     

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?     

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.     

Timing effects on first marriage: twentieth-century experience in England and Wales and the USA

Recent substantial declines in first marriage in Western countries have been accompanied by increases in the average age at first marriage. Since the period proportion ever marrying, PEM, is sensitive to cohort tempo changes, the recent fall in the PEM may simply reflect cohort delays in marriage. The importance of timing factors is examined in the light of twentieth-century experience of first marriage in England and Wales and the USA. Using a variant of the Timing Index developed in research on fertility, we measure cohort timing effects for marriage and calculate an adjusted PEM. After examining twentieth-century trends in nuptiality for men and women, we find substantial tempo effects on the period PEM. Adjusted PEM values show a real decline in marriage for cohorts, but that decline is considerably smaller than the one shown by the unadjusted figures. This is especially true for England and Wales, where the decline in marriage was much greater.     

Multivariate analysis of parity progression—based measures of the total fertility rate and its components

This article describes a methodology for applying a discrete-time survival model—the complementary log-log model—to estimate effects of socioeconomic variables on (1) the total fertility rate and its components and (2) trends in the total fertility rate and its components. For the methodology to be applicable, the total fertility rate (TFR) must be calculated from parity progression ratios (PPRs). The components of the TFR are PPRs, the total marital fertility rate (TMFR), and the TFR itself as measures of the quantum of fertility, and mean and median ages at first marriage and mean and median closed birth intervals by birth order as measures of the tempo or timing of fertility. The focus is on effects of predictor variables on these measures rather than on coefficients, which are often difficult to interpret in the complex models that are considered. The methodology is applicable to both period and cohort data. It is illustrated by application to data from the 1993, 1998, and 2003 Demographic and Health Surveys (DHS) in the Philippines.     

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.     

Low Fertility Trap:Theories,Facts and Implications

The low Fertility Trap Hypothesis proposes that there are three self-reinforcing mechanism--demographic,sociological and economic,working towards a downward spiral in future fertility.Once TFR drops below 1.5,it will be difficult to recover.The fertility recovery emerging in many countries across the world has changed the lowfertility trap theory and also the justification of the theory itself.So low-fertility trap is more likely a pattern summarized from a short-time phenomenon than a generalized social law.As with China,the current fertility level is above 1.5 births per woman,and China is not in the "Low-fertility trap".Moreover,most recent surveys suggests that current fertility intention in China is above 1.8 births per woman and more than60 percent of people would have a second child if there is an adjustment of fertility policy.In addition,birth postponement is still playing an important role in reducing TFR in China.Thus,with the high fertility intention,adjustment of family planning policy and decreasing tempo effect,TFR in China will experience upturn but not further decline in the near future.It is lack of evidence to conclude that China has already been or is going to be trapped in low fertility.     

浅析中国1991～2000年生育模式变化对生育水平的影响

分析生育模式的变化对生育水平的影响 ,通过计算 1 991～ 2 0 0 0年中国去进度效应总和生育率TFR’ ,清楚地看出 ,提高初婚年龄和拉大一孩至二孩生育间隔所造成的生育模式的变化导致中国 1 0年间TFR偏低。去进度效应总和生育率TFR’较之TFR更加接近中国妇女的实际终身生育水平     

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.     

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.     

The Unfolding Story of the Second Demographic Transition

This article presents a narrative of the unfolding of the Second Demographic Transition (SDT) since the theory was first formulated in 1986. The first part recapitulates the foundations of the theory, and documents the spread of the SDT to the point that it now covers most European populations. Also for Europe, it focuses on the relationship between the SDT and the growing heterogeneity in period fertility levels. It is shown that the current positive relationship between SDT and TFR levels is not a violation of the SDT theory, but the outcome of a “split correlation” with different sub‐narratives concerning the onset of fertility postponement and the degree of subsequent recuperation in two parts of Europe. The second part of the article addresses the issue of whether the SDT has spread or is currently spreading in industrialized Asian countries. Evidence gathered for Japan, South Korea, Hong Kong, Singapore, and Taiwan is presented. That evidence pertains to both the macro‐level (national trends in postponement of marriage and parenthood, rise of cohabitation) and the micro‐level (connections between individual values orientations and postponement of parenthood). Strong similarities are found with SDT patterns in Southern Europe, except for the fact that parenthood is still very rare among Asian cohabiting partners.     

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.     

Variance effects in the bongaarts-feeney formula

Bongaarts and Feeney have recently proposed an adjusted total fertility rate to disentangle tempo effects from changes in the quantum of fertility. We propose an extension to the Bongaarts and Feeney formula that includes variance effects: that is, changes in the variance of the fertility schedule over time. If these variance effects are ignored, the mean age at birth and the adjusted total fertility rate are biased. We provide approximations for these biases, and we extend the TFR adjustment to fertility schedules with changing variance. We apply our method to the Swedish baby boom and bust, and show that variance effects are important for evaluating the relative contributions of tempo and quantum effects to the fertility change from 1985 to 1995.     

Changes in the Quantum of Russian Fertility During the 1980s and Early 1990s

To investigate whether Russia's dramatic fertility changes pre‐ and post‐Soviet times were due primarily to tempo effects, as has been argued recently, or to quantum effects, this study standardizes for factors that distort conventional fertility indexes. A time series spanning 1978–93 of period parity‐progression ratios for the Russian Federation is constructed applying the PADTFR technique, which takes into account age, parity, and time elapsed since the birth of the previous child, to data from the Russian micro census of February 1994 (2.8 million maternity histories). Both the fertility rise of the 1980s and the fertility fall of the early 1990s are found to be primarily due to changes in the probability of a second birth. The impact of tempo on the conventional TFR is significant, but of relatively minor magnitude in comparison to changes in the quantum of fertility. The social and economic context in which the fertility change took place is described.     

The fertility impact of changes in the timing of childbearing in the developing world

This study examines the role of tempo effects in the fertility declines of less developed countries. These effects temporarily inflate the total fertility of a population during periods when the age at childbearing declines and deflate it when childbearing is postponed. An analysis of data from the World Fertility Surveys and the Demographic and Health Surveys demonstrates that fertility trends observed in many less developed countries are likely to be distorted by changes in the timing of childbearing. In most countries women are delaying childbearing, which implies that observed fertility is lower than it would have been without tempo changes. This pattern is most clearly documented in Taiwan, where accurate birth statistics from a vital registration system make it possible to estimate the tempo components of fertility annually from 1978 to 1993. The small but unexpected rise in the total fertility of Colombia in the early 1990s is attributed to a decline in the negative tempo distortion that prevailed in the 1980s. Similar interruptions of ongoing fertility declines may occur in the future in other countries when existing negative tempo effects are removed.     

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.