Family-building in a Canadian City: An analysis of the timing and spacing of pregnancies

Conjugal and maternity histories collected in an Ottawa Survey permit a cohort analysis of fertility change through an examination of pregnancy intervals. The paper discusses the use of life-table techniques to overcome specified censoring biases. Inter-generational changes in fertility behaviour are identified and differences at higher parities, and between the youngest and other cohorts at parity zero are noted. Finally, a relationship is established between the order of a birth interval and its duration.     

Probabilistic Forecasting Using Stochastic Diffusion Models, With Applications to Cohort Processes of Marriage and Fertility

In this article, we show how stochastic diffusion models can be used to forecast demographic cohort processes using the Hernes, Gompertz, and logistic models. Such models have been used deterministically in the past, but both behavioral theory and forecast utility are improved by introducing randomness and uncertainty into the standard differential equations governing population processes. Our approach is to add time-series stochasticity to linearized versions of each process. We derive both Monte Carlo and analytic methods for estimating forecast uncertainty. We apply our methods to several examples of marriage and fertility, extending them to simultaneous forecasting of multiple cohorts and to processes restricted by factors such as declining fecundity.     

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?     

Forecasting births in Greater London: An application of the easterlin hypothesis

Summary A model for forecasting fertility is proposed in which an attempt is made to represent the cyclical fluctuations in fertility typical of developed societies. R. A. Easterlin has put forward the hypothesis that relative affluence, i.e. tension between material aspirations and resources, is an important determinant of fertility behaviour. Relative cohort size in turn affects relative affluence, because the size of a cohort influences its competitive position in the labour market. However, predictions based on relative cohort size alone neglect other sources of periodic fluctuations in fertility, such as those arising from generational cycles. A periodic component which expresses fertility variations as a direct function of time is, therefore, included in this model. A time series of age-specific fertility rates and population estimates for England and Wales and for Greater London is used to assess the relationship between fertility, relative cohort size, and the periodic time function. There is evidence of significant cyclic effects and some support for the Easterlin hypothesis in that the fertility of younger age groups is inversely related to the relative size of older cohorts. Projections are made of the future trend in total fertility assuming a continuation of the observed relationship. Use of different assumed periodicities permits the generation of variant projections of fertility.     

A fertility analysis of New Zealand marriage cohorts

New Zealand annual returns of non-Maori live legitimate births 1913 to 1955 were tabulated longitudinally by marriage duration and birth order. The figures were used as numerators of fertility rates of forty marriage cohorts, specific for duration and birth order ; the twenty-four oldest cohorts had virtually completed fertility. For the denominators of the rates, the cohorts of initial size (estimated by a method similar to that described by P. H. Karmel) were survived by observing changes over time through divorce, death, widowhood, war-widowhood, and net external migration. The aim was to provide a set of data of the best possible approximation on variations of cohort fertility.

Total cohort rates, cumulated for twenty years’ duration of marriage, and segmental rates of relevant sub-periods are given for parities o to 7+. Total rates of the cohorts of completed fertility yielded values of family size, and were also used for parity progression ratios (by L. Henry’s formula). Segmental rates permitted a study of changes in timing maternities.

The analysis, which needs as a corollary a nuptiality analysis, is concerned, so far with past experience. It confirms the decline in number and proportion of large families. Both the parity progression ratios, and segmental rates of cohorts of as yet incomplete fertility, suggest some recent recovery in three- and fourchild families. For total fertility, such recovery might even be more significant than the observed decline in large families. On the other hand, birth-order specific changes in timing suggest lengthening of intervals among older cohorts as a trend upon which is superimposed the fluctuation due to postponement of, and recovery of a portion of postponed maternities. A construction of hypothetical timing patterns for incomplete cohorts by a simplified method of projection does not lead very far without support of observations on spacing that differentiate for family size.     

The Quality of Male Fertility Data in Major U.S. Surveys

Researchers continue to question fathers’ willingness to report their biological children in surveys and the ability of surveys to adequately represent fathers. To address these concerns, this study evaluates the quality of men’s fertility data in the 1979 and 1997 cohorts of the National Longitudinal Survey of Youth (NLSY79 and NLSY97) and in the 2002 National Survey of Family Growth (NSFG). Comparing fertility rates in each survey with population rates based on data from Vital Statistics and the U.S. Census Bureau, we document how the incomplete reporting of births in different surveys varies according to men’s characteristics, including their age, race, marital status, and birth cohort. In addition, we use Monte Carlo simulations based on the NSFG data to demonstrate how birth underreporting biases associations between early parenthood and its antecedents. We find that in the NSFG, roughly four out of five early births were reported; but in the NLSY79 and NLSY97, almost nine-tenths of early births were reported. In all three surveys, incomplete reporting was especially pronounced for nonmarital births. Our results suggest that the quality of male fertility data is strongly linked to survey design and that it has implications for models of early male fertility.     

Starting age and subsequent birth intervals in cohabitational unions in current danish cohorts, 1975

This paper presents some main results of an investigation by life table methods of birth interval data in cohabitational unions (marriages as well as consensual unions) in current Danish cohorts. Our results confirm previous findings that an early age at the start of recorded exposure to childbearing risk is indicative of a rapid pace and high level of subsequent fertility. The analysis modifies previous results and adds several new details regarding cohort trends and the effect of parity at the start of reported cohabitation. For each parity within a period of cohabitation, fertility differentials by reported starting age seem to have diminished from our older cohorts (of age up to 49 years in 1975) to our younger ones (of age less than 30 years in 1975). There are indications of a dramatic change in childbearing behaviour following the arrival of novel attitudes to non-marital cohabitation and childbearing in Denmark about 1967.     

A cost of living longer: Projections of the effects of prospective mortality improvement on economic support ratios for 14 advanced economies

The economic implications of increasing life expectancy are important concerns for governments in developed countries. The aims of this study were as follows: (i) to forecast mortality for 14 developed countries from 2010 to 2050, using the Poisson Common Factor Model; (ii) to project the effects of the forecast mortality patterns on support ratios; and (iii) to calculate labour force participation increases which could offset these effects. The forecast gains in life expectancy correlate negatively with current fertility. Pre-2050 support ratios are projected to fall most in Japan and east-central and southern Europe, and least in Sweden and Australia. A post-2050 recovery is projected for most east-central and southern European countries. The increases in labour force participation needed to counterbalance the effects of mortality improvement are greatest for Japan, Poland, and the Czech Republic, and least for the USA, Canada, Netherlands, and Sweden. The policy implications are discussed.     

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).     

Constructing fertility tables for Soviet populations

Because the 1970 Soviet Union census does not provide information on the age structure of men and women separately by sex and according to their ethnic affiliation, the 1959 USSR census data serve as the basis to infer knowledge about ethnic fertility. The model takes into account (1) the total number of births in 1960, estimated from the child-woman ratio in 1959, (2) the age structure of women in 1959, and (3) the assumed pattern of age-specific birth rates structured in terms of the modal age at childbearing and the length of the fertility age span. The results show that Ukrainians among the Slav populations ranked as the lowest with 2.07 children born per woman. Their total fertility contrasts with that of Kazakhs native to Central Asia, who reportedly according to Soviet sources had 7.46 children per woman in 1958-1959, and whose estimated rate is around 8.59 children. Extreme variations appear in the estimates of fertility among nationalities of the Caucasus region, Volga Basin, and to a lesser degree in Siberia. Official Soviet calculations of crude birth rates and age-specific rates for 15 Union Republics in 1967-1968 are transcribed and compared with the estimates for nationalities in 1959-1960. The same theoretical model used to generate the Soviet rates may be adapted under different assumptions to non-Soviet populations in other situations where the data are scanty or incomplete.     

Cohort Parity Analysis and Fertility Transition Dynamics: Reconstructing Historical Trends in Fertility Control from a Single Census

The Cohort Parity Analysis (CPA) method for the indirect measurement of the extent of marital fertility control makes use of parity distribution data of the kind reported, for specified marriage duration and marriage-age (or current age) groups of women, by a fertility census. Corresponding to every such distribution, CPA yields efficient upper and lower bounds on the proportion of controllers in the specified cohort, as well as bounds for the parity distribution of the controllers. As the women who belong to different marriage cohorts are observed at different durations of marriage in a census, it is possible to infer inter-cohort trends in the extent of fertility control (at some specified marriage duration(s)) if one knows the time pattern of the adoption of control among the members of each cohort. It is shown in this paper that robust estimates of the intracohort diffusion pattern can be obtained from the census cross-section itself, by supplementing the basic assumptions of the CPA framework with a plausible assumption about the behaviour of the ‘representative’ controller in a given cohort. The estimation technique is illustrated by applications to data for married women in urban Eire from the Census of Ireland in 1911, and to native white married women in the U.S. South from the U.S. Census of 1910.     

Evolution of fertility and mortality

Historical and current fertility trends in both Quebec and Canada as a whole are surveyed. While fertility among French Canadians was higher than that in neighboring provinces until the mid-20th century, in 1968 Quebec's crude birthrate was the lowest in Canada, and in 1972 it was 13.8 vs. 15.9 (the national birthrate). This reversal is explained in terms of the demographic transition theory, the declining influence of organized religion, and new opportunities for social mobility for minority groups. The birthrate throughout Canada is also declining. Although recent cohort studies are incomplete because women have not yet finished their reproductive years, it appears that completed family size will be lower than at any time in Canadian history. The period total fertility rate indicates an average family size of 1.8 children in 1976, but it is unclear whether this represents an actual reduction in family size or the postponement of childbearing. The sharpest fertility decline has been among women aged 35-49, but peak fertility rates have shifted from the 20-24 age group to those aged 25-29. Fertility is negatively related to education, and the lowest fertility is found among the intermediate income groups. Since the 1969 lifting of the ban on contraceptive sales and advertising, family planning activities have been stepped up. Also removed was the total ban on abortion. In 1975 there were 14.9 therapeutic abortions per 100 live births, but it has been charged that abortion standards are being applied inequitably from hospital to hospital.     

Fertility patterns among religious groups in Canada

The U shape that has been traced out by the crude birth rate in the United States and Canada is well known. Falling birth rates reached a low point in the mid-1930’s; the rate rose to a peak in 1947 and remained high through the 1950’s. In terms of cohorts, completed family size was smallest for women born around 1910, whose childbearing was concentrated in the 1930’s. With data from the 1961 census of Canada, trends in cohort marital fertility by religion are examined. The U pattern appears for both Protestants and Jews. For Catholics, a reversal in the downward trend of family size had not appeared by 1961, although the U pattern can be discerned for some subgroups such as Catholics living in big cities and persons of Irish ancestry. In the United States, however, changes in family size for all three religious groups and both whites and nonwhites follow the U pattern. Religious differentials in family size in Canada have been decreasing, but they remain much larger than either religious or color differentials in the United States, which show no decrease. The distinctive features of Catholic fertility in Canada are most pronounced among the regionallyconcentrated French Canadians, suggesting an interplay of religious, regional, and ethnic influences.     

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.     

Increasingly heterogeneous ages at first birth by education in Southern European and Anglo-American family-policy regimes: A seven-country comparison by birth cohort

According to the 'reproductive polarization' hypothesis, family-policy regimes unfavourable to the combination of employment with motherhood generate greater socio-economic differentials in fertility than other regimes. This hypothesis has been tested mainly for 'liberal' Anglo-American regimes. To investigate the effects elsewhere, we compared education differentials in age at first birth among native-born women of 1950s and 1960s birth cohorts in seven countries representing three regime types. Women with low educational attainment have continued to have first births early, not only in Britain and the USA but also in Greece, Italy, and Spain. Women at all other levels of education have experienced a shift towards later first births, a shift that has been largest in Southern Europe. Unlike the educationally heterogeneous changes in age pattern at first birth seen under the Southern European and Anglo-American family-policy regimes, the changes across birth cohorts in the study's two 'universalistic' countries, Norway and France, have been educationally homogeneous.     

Age–Period–Cohort Decomposition of U.S. and Japanese Birth Rates

Aggregate data on birth rates in the U.S. and Japan, classified by period and by age, are decomposed into age, period, and cohort effects using Bayesian cohort models that were developed to overcome the identification problem in cohort analysis. Main findings are fivefold. First, age, period, and cohort effects movements are all larger in Japan than in the U.S. Second, in both countries, age effects are the largest and are roughly consistent with the life-cycle movements showing an inverted U shape. Third, Easterlin’s cohort size hypothesis roughly fits U.S. birth rates but not Japanese birth rates. Fourth, despite rapid decline of total fertility rates in Japan in last three decades, period effects have been on an upward trend since the early 1990s. Finally, upward and downward cohort effects movements in Japan are derived by rapid economic growth and the Equal Employment Opportunity Law, respectively.     

Toward a general analysis of endogenous Easterlin cycles

Easterlin believed that there were two features associated with the birth cycles he observed: the cycles were related to the labor market, and they might be self-generating. This paper tries to set up a model that contains both of these two features. We suppose that the welfare of various age-specific cohorts are determined by their respective marginal productivity, and that the underlying technology which puts together labor force of various age-specific cohorts can be characterized by a general production function. Under these weak assumptions, we show that the well-analyzed cohort and period models along the lines of Lee (1974) are restricted versions of our general setting. Given that both the cohort model and the period model were rejected by statistical tests, we adopt the coefficient values obtained from the estimation of the unrestricted version to perform the bifurcation analysis. We go beyond the previous study which focused upon the possible existence of limit cycles, and show that the U. S. fertility limit cycle solution is unstable. Therefore the population trajectory will never converge to that limit cycle.We thank Professors Kenneth Wachter, Shripad Tuljapurkar, and two anonymous referees for their valuable help, comments and suggestions.     

A cohort analysis of the timing of first birth and fertility in Ghana

This paper examines the nature of the inverse association between age at first birth and fertility across successive generations of Ghanaian women. Within the context of enhanced non-marital opportunities for contemporary women and declining fertility, we develop a rationale for and test the hypothesis that in a medium fertility environment as currently found in Ghana, the effect of age at first birth on fertility becomes more important than ever before. Five birth cohorts were identified (1938–1944; 1945–1949;1950–1954; 1955–1959; 1960–1964)from a merged file of the 1988, 1993 and 1998 Ghana Demographic and Health Surveys. The analyses were restricted to women over 35 years old at the time of the surveys, which allowed us to use current parity as a reasonable proxy for completed fertility. Preliminary results suggest that women who had first births early tend to have a higher number of births than those whose first births occur late, regardless of birth cohort. In multivariate analyses, the effect of age at first birth as a determinant of fertility was found to be more substantial among later cohorts. The implications of the findings are discussed.     

Cohort estimates of nonmarital fertility for U.S. Women

Historical trends in U.S. nonmarital fertility have been compiled almost exclusively from vital statistics on births. This paper complements this historical record by providing cohort estimates of nonmarital fertility for cohorts of U.S. women spanning approximately 50 years of cohort experience. Life table estimates using retrospective marital and fertility histories in the June 1980, 1985, 1990, and 1995 Current Population Surveys reveal nonnegligible levels of nonmarital fertility historically. For women born between 1925 and 1929, nearly 1 in 10 had at least one nonmarital birth by age 30. For women born between 1965 and 1969, more than 1 of 4 had one or more nonmarital births by age 30, with roughly 1 of5 white, 3 of 5 black, and 1 in 3 Hispanic women having at least one nonmarital birth by age 30. Life table estimates reveal a twofold increase between ages 20 and 30 in the percentage of women with at least one child outside of formal marriage for all cohorts of white and Hispanic women, and an increase of roughly two-thirds for all cohorts of black women. I also document qualitative differences in nonmarital fertility by race/ethnicity, with the percentage of nonmarital births following a divorce or marital separation for white women approximately twice that for black or Hispanic women. Finally, I introduce a new measure, the cohort nonmarital fertility ratio (CNMFR), which provides a cohort complement to the standard period nonmarital fertility ratio. Conservative estimates reveal a roughly threefold increase in the CNMFR for women born from 1925-1929 to 1950-1954 for both whites and blacks, despite substantially higher levels of nonmarital fertility among black women. Overall, these findings reveal surprisingly high levels of nonmarital fertility for women born since the 1920s and confirm that nonmarital fertility has become an increasingly substantial component of overall U.S. fertility.     

The comparative analysis of the dynamics of childbearing women's birth at Yanging County, Beijing]

At the end of 1981 Yanging County had 26 communes, 375 production brigades and a total population of 211,098. A random sampling of 5.07% of the production brigades was taken, which included teams from the plains as well as mountainous regions. The sample had a population of 10,888, or 5.16% of the entire county, among whom 189 subjects were interviewed. These 189 women, whose ages ranged from 35-67, were divided into 5 birth year cohorts (1914, 1920, 1930, 1940, 1946). Findings include: 1) Age at marriage: the average age at marriage (about 17 years) between the 1914 and 1946 groups rose 1.82 years, indicating that early marriage was the norm. The time between marriage and 1st birth has shortened. 2) Fertility data: from 1914 to 1946 the lifetime fertility rate tended to decline from 4.60 to 3.70, but the 1930 cohort was the highest (6.42), followed by the 1920 cohort (6.26). The fertility rate of the 1914 cohort tended to rise in the 1950s after already having reached a peak in the early 1940s, probably because after Liberation fertility rose due to a higher standard of living and a stablized society. The fertility of the 1930 cohort was highest around 1963 when they were already 30 years old. The fertility of the 1940 cohort was also highest beginning around 1963. In both cases, the reason probably was because the national economy improved at this time. Indeed, the national fertility rate rose from a 1960 low of 20.9/1000 to 43.6/1000 in 1963. 3) Contraceptive use: prior to 1972 before there was an offical birth control policy, a sizeable number of women already desired to use contraceptives, the reason being most of these women felt they already had enough children. However, many women did use contraceptives in response to the call to do so. 4) Factors influencing fertility standards: in general, the less a woman's education and the lower her income, the higher was her standard of fertility, and vice versa. 5) The percentage of women who had children who died before the age of 15 ranged from 35.9% of the 67 year olds to 12.6% of the 35 year olds.