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.     

Measuring marital fertility control with CPA

Cohort Parity Analysis (CPA) is an indirect method for measuring the extent and timing of the adoption of fertility control within marriage. Cohort Parity Analysis uses 2 sets of parity distributions, 1 from the population under study (the "target" population) and 1 from a similar population in which fertility control is absent (the "model" population). Fertility control is defined as any set of behaviors in the target population that cause its parity progression rates to differ from those of a similar but noncontrolling population. The target population contains an unidentified mixture of controlling and noncontrolling couples for a given age range and marriage duration. The model population is similar in all respects except that it contains no controllers. Examples are taken from urban and rural Irish populations in the 1911 census data. Cohort parity analysis rests on 2 basic assumptions: 1) For every specified marriage duration and marriage age, there exists some parity above which controllers are never found; and 2) Parity progression rates of those in the mixed population who have never initiated fertility control are identical to those in the model population. Further, one must identify a cutoff parity beyond which controllers are presumed not to be found. In these urban Irish examples cutoff parity for each marriage age and duration is set at 20% of that of the noncontrolling rural Irish population. The upper and lower bounds on the percentage of controllers are derived by obtaining the lower and upper bounds on the size of the group at that parity who never controlled and subtracting these estimates from the observed percentage of the target population observed at that parity. Flow charts are used to present the methodology of cohort parity analysis in a simple format. the method is illustrated in the case of Ireland in 1911. Aggregate parity distributions for the county boroughs of Dublin, Belfast, Cork, LOndonderry, Limerick, and Waterford are taken as the target distribution; and parity distributions for those living outside the county boroughs are taken as the model distributions. The analysis shows that 28% of urban-dwelling Irish women who married before age 30 and were married between 4 and 29 years in 1911 used some effective means of fertility control. The parity distributions also show that women who married later controlled their fertility to a greater extent and that between 20.9 and 25.5% of women married 4 years in 1911 had already practiced fertility control by 1911, but only 15.5% of those married 15-19 years had used fertility control by 1911. Cohort Parity Analysis is thus a useful method of examining historical populations in the process of fertility transition.     

Delayed Marriage and Very Low Fertility in Pacific Asia

The general decline in fertility levels in Pacific Asia has in its vanguard countries where fertility rates are among the lowest in the world. A related trend is toward delayed marriage and nonmarriage. When prevalence of cohabitation in European countries is allowed for, levels of “effective singlehood” in many countries of Pacific Asia have run ahead of those in northern and western Europe. This raises questions about the extent to which delayed marriage has been implicated in fertility declines, and whether the same factors are leading both to delayed marriage and to lowered fertility within marriage. The article argues that involuntary nonmarriage is likely to be more common in Pacific Asia than in Western countries, and that resultant involuntary childlessness plays a substantial role in the low fertility rates currently observed.     

Does an effect of marriage duration on pre-transition fertility signal parity-dependent control? An empirical test in nineteenth-century Leuven,Belgium

It has been demonstrated for many pre-industrial populations that the age at marriage, or marriage duration, influences age-specific marital fertility but the reason for this remains unclear. Among the several mechanisms that may be responsible, the following are often cited: secondary sterility or increased subfecundity associated with parity; declining coital frequency; the age difference between the spouses; and, importantly, parity-dependent fertility control. If the latter mechanism were partly responsible for the marriage-duration effect in pre-transition populations, it would contradict the concept of the modern fertility transition as the evolution (or revolution) from parity-independent to parity-dependent fertility. The study presented in this paper investigates the relative importance of these alternative explanations. The application of multivariate Poisson regression to the fertility data from two birth cohorts in the Belgian city of Leuven shows that a linearly declining or even concave age-specific fertility pattern, disaggregated by age at marriage, does not imply parity-dependent fertility limitation.     

On the tempo of childbearing in England and Wales

Abstract The paper describes a computerized model developed to simulate the fertility of a hypothetical marriage cohort in a closed population. The model was applied to England and Wales fertility data of marriage cohorts of the years 1951 to 1970. For each of these cohorts, the computer was programmed to construct five series of tables showing birth-order probabilities, family size frequency distribution, mean length of intervals between marriage and successive births, parity progression ratios and mean family sizes of fertile women. The results showed that the fertility of the cohorts of women who married between the middle 1950s and the early 1960s was character ized by a declining trend in the frequency of childlessness and by a dramatic increase in the proportion of marriages with two or more children. Since 1964 or so, there has been a downward trend in duration-specific birth-order probabilities. The analysis suggests that the recent drop in fertility may well prove to be the effect of an upward shift in the timing of births as well as a fall in completed fertility.     

Fertility decline in Taiwan: A study using parity progression ratios

Taiwan's decline in fertility is studied by using period parity progression ratios. Levels of marriage and motherhood are found to have been high and essentially constant though the late 1980s, suggesting that the decline has been due almost entirely to declines in second and higher order-births. Families with three or more children play an important role in maintaining the current level of fertility. The level of fertility would be even lower without these families. They contributed more than one-half child per woman to the total fertility rate during most of the 1980s. Total fertility rates computed from the period parity progression ratios indicate a substantially higher level of fertility than the conventional total fertility rate; they remained above or at replacement level through 1988. A formal demographic analysis suggests that the conventional total fertility rate has been depressed by shifts in age at childbearing.     

Mortality,marriage, and growth in pre-industrial populations

It has been widely assumed that in pre-industrial European populations postponement of marriage was a major check on fertility, and that marriage was contingent upon access to a livelihood in the form of a homestead or a craft. Death made room for new families, and the age at inheritance might therefore be an index of the age at marriage. High mortality should then mean early marriage and high fertility. When the effect of a uniform increase in the force of mortality on the “natural rate of growth” is estimated quantitatively, it is found that fertility response is of the same magnitude as the change in mortality so that within a wide range mortality differentials alone would not suffice to account for persistent differentials in growth rates. The assumption of a reasonably effective control through the prudential check is thus strengthened.     

Nuptiality and fertility of birth cohorts

The impact of changes in age patterns of nuptiality on the net reproduction rate is examined using life table techniques and assuming that age-specific fertility within marriage and fertility outside of marriage are fixed. In the second section, a standardization technique is used to investigate the impact of changes in nuptiality on age-cumulative measures of marital fertility. Examples using data for selected generations of Australian women demonstrate the extent to which recent changes in average completed family size in Australia were affected by changing nuptiality patterns.     

A reassessment of the demography of traditional rural China

An analysis of the composition, characteristics, and vital processes of the population of rural mainland China was undertaken using data collected as part of a study of land utilization carried out by Naking University in 1929-1931. These data have been reappraised using techniques for demographic analysis of faulty data which shows a consistent picture of the Chinese farmer of high morta moderate fertility, and early and universal marriage. Estimates of the singulate mean age at marriage was 17.5 for females and 21.3 for males. Fewer than 1 in 1000 women and 3 in 1000 men never married. The reported parity of older women was only slightly above 5, which disputes the very large historical family size that has been imputed to the chinese. There was a life expectancy of less than 25 years for each sex, and very high infant mortality. These characteristics were of sufficient persistence to have generated a stable age distribution.     

Presentation and establishment of a system of total progressive fertility rates and relevant models

Demographic studies necessarily rely on adequate and accurate statistical data. To take into consideration China's present situation of population control and planned birth practice, a system of total progressive fertility rate (TPFR) different from the parity progression ratio is established and its relevant model presented in order to make indicators used in analysing women's 1st marriage and fertility level reflect as closely as possible the actual situation. Here, TFR and TPFR, both used in analyzing fertility level, are compared so as to show that TPFR is a methodology more appropriate for use in the analysis of China's fertility. The model is based on the fact that women's vital events happen progressively from being born to completing childbearing. In composing the model, both women's age structure and parity structure are considered and the regularity of their changes with different years is defined. In China, the population development program has been brought into the overall social and economic development plan. Thus it is necessary to practice planned birth in order to make the population develop in a way which is in keeping with the social and economic development. Compared with other models or theories, it is more realistic to use the model discussed above in studies on China's population policy.     

Lifetime probability of additional births by age and parity for American women, 1935–1968: A new measurement of period fertility

A new fertility measurement, probability that a woman of specified parity and age will bear a given number of births in her remaining lifetime, is proposed in this article. The measurement is a summary index of a set of age-parity-specific birth probabilities and in a particular case it is conceptually analogous to the total fertility by birth order but free from the influence of the parity distribution. Fertility of American women for the period 1935-1968 was studied by use of such lifetime probabilities. It appears that the trend of fertility of high birth orders has been parallel with that of low orders. Initiation of the recent decline in fertility depends on parity and age of woman.     

Changes in fertility expectations and preferences between 1962 and 1977: Their relation to final parity

Changing fertility expectations and preferences from 1962 to 1977 are compared with final parity in a longitudinal study. Results are strongly affected by initial parity in 1962. Final parity, 27 percent below expectations for those initially childless, illustrates the effect for couples free to change expectations downward of declining fertility preferences. Changes in expectations early in marriage had a significant long-term effect on final parity, as did early differences between wife’s expectations and husband’s preferences. Unplanned births increased final parity significantly. Religion, education, and income had no systematic relation to the discrepancy between initial expectations and final parity.     

Birth spacing and fertility limitation: a behavioral analysis of a nineteenth century frontier population

Our analysis of changing birth interval distributions over the course of a fertility transition from natural to controlled fertility has examined three closely related propositions. First, within both natural fertility populations (identified at the aggregate level) and cohorts following the onset of fertility limitation, we hypothesized that substantial groups of women with long birth intervals across the individually specified childbearing careers could be identified. That is, even during periods when fertility behavior at the aggregate level is consistent with a natural fertility regime, birth intervals at all parities are inversely related to completed family size. Our tabular analysis enables us to conclude that birth spacing patterns are parity dependent; there is stability in CEB-parity specific mean and birth interval variance over the entire transition. Our evidence does not suggest that the early group of women limiting and spacing births was marked by infecundity. Secondly, the transition appears to be associated with an increasingly larger proportion of women shifting to the same spacing schedules associated with smaller families in earlier cohorts. Thirdly, variations in birth spacing by age of marriage indicate that changes in birth intervals over time are at least indirectly associated with age of marriage, indicating an additional compositional effect. The evidence we have presented on spacing behavior does not negate the argument that parity-dependent stopping behavior was a powerful factor in the fertility transition. Our data also provide evidence of attempts to truncate childbearing. Specifically, the smaller the completed family size, the longer the ultimate birth interval; and ultimate birth intervals increase across cohorts controlling CEB and parity. But spacing appears to represent an additional strategy of fertility limitation. Thus, it may be necessary to distinguish spacing and stopping behavior if one wishes to clarify behavioral patterns within a population (Edlefsen, 1981; Friedlander et al., 1980; Rodriguez and Hobcraft, 1980). Because fertility transition theories imply increased attempts to limit family sizes, it is important to examine differential behavior within subgroups achieving different family sizes. It is this level of analysis which we have attempted to achieve in utilizing parity-specific birth intervals controlled by children ever born.(ABSTRACT TRUNCATED AT 400 WORDS)     

The Baby Boom and Its Causes: What We Know and What We Need to Know

This study analyzes the timing, magnitude, and volume of the mid‐twentieth century baby boom in European and non‐European Western countries. The baby boom is found to have been especially strong in the non‐European countries, fairly strong in some European countries, and quite weak in others. While the boom has often been linked with postwar economic growth and the recuperation of births postponed during the Depression era, we argue that this is only a limited part of the story. In most cases the recovery of the birth rate started well before the end of World War II, a fact not accounted for by existing theories. We investigate the roles played by the recovery of period as well as cohort fertility, the underlying marriage boom, and the recovery of marital fertility. We identify major puzzles for future research, including the reasons for strongly declining ages at marriage and the role played by contraceptive failure in the rise of high‐parity births.     

Age,biological factors,and socioeconomic determinants of fertility: A new measure of cumulative fertility for use in the empirical analysis of family size

To influence the number of children ever born to a woman, socioeconomic variables must operate through behavioral and biological mechanisms such as the age at marriage, the level of fertility in the absence of deliberate fertility control, and the level of control exerted to reduce fertility within marriage. In this paper, we propose a new measure of cumulative fertility which is standardized for the age-fecundity relationship and for exposure to the risk of conception associated with duration of marriage. A simple model of fertility behavior which incorporates some of the mechanisms through which socioeconomic factors may affect fertility is developed and applied to data from the United States to demonstrate the properties of alternative measures of family size. The results indicate that use of the new measure allows more precise estimates of socioeconomic fertility relationships than would be obtained with children ever born or by sample stratification.     

A model of the age patterns of births by parity in natural fertility populations

This research develops a convolution model to express the age patterns of fertility at each birth order in natural fertility populations in terms of six parameters, directly representing the proximate determinants of fertility, and a series of parity level indicators. The parity level indicators at each birth order are simply the proportions of women in a cohort who will eventually have births at each birth order it the age‐related fecundity decline is controlled. The Coale‐McNeil nuptiality model is adopted to represent the age pattern of first marriage rates and the natural fertility schedule employed in the Coale‐Trussell fertility model is incorporated to adjust age effects. The fast Fourier transform is used in solving the model numerically. It proves that the model is able to provide excellent fits to fertility for rural Chinese women in the 1950s.     

The construction of the fertility model of variable parity from family planning practice]

Understanding the changing patterns of age specific fertility under the planning system is essential for building a fertility model which reflects birth control policy implementation in China. In building a Parity Variable Fertility Model, 4 basic elements are to be considered: 1) psychosocial, and physiological variables, 2) patterns of the total fertility rate and age-specific fertility rate, 3) socioeconomic development, and 4) distribution of parity-specific fertility. THe natural fertility of women is 17, calculated from a 309-years childbearing period, with 17% of non-susceptible time. In China, about 86% of natural fertility is suppressed by various factors. In this model, the following variables are included: 1) The first marriage ratio, which is the proportion of women in each age group which enters into a first marriage. The range and spread of this ratio is closely associated with the first birth. 2) The first birth ratio, which is the proportion of a marriage cohort to have a first birth each year. 3) the birth interval, which determines the distribution of second births. 4) Regulation coefficient B, which represents birth control regulations which approximately determine the number of second-parity or higher order births. The difference between the fertility level generated from the Parity Variable Fertility Model and reality depends on the implementation of birth control program, the assumptions on regulation coefficients, and changes in social and cultural factors. The model is easy to use, especially for areas where the marriage and fertility records of women of child-bearing are well kept.     

Multidimensional Life Table Estimation of the Total Fertility Rate and Its Components

Using discrete-time survival models of parity progression and illustrative data from the Philippines, this article develops a multivariate multidimensional life table of nuptiality and fertility, the dimensions of which are age, parity, and duration in parity. The measures calculated from this life table include total fertility rate (TRF), total marital fertility rate (TMFR), parity progression ratios (PPR), age-specific fertility rates, mean and median ages at first marriage, mean and median closed birth intervals, and mean and median ages at childbearing by child’s birth order and for all birth orders combined. These measures are referred to collectively as “TFR and its components.” Because the multidimensional life table is multivariate, all measures derived from it are also multivariate in the sense that they can be tabulated by categories or selected values of one socioeconomic variable while controlling for other socioeconomic variables. The methodology is applied to birth history data, in the form of actual birth histories from a fertility survey or reconstructed birth histories derived from a census or household survey. The methodology yields period estimates as well as cohort estimates of the aforementioned measures.     

Japan’s changing fertility mechanisms and its policy responses

This paper discusses Japan’s decline in fertility over the past 50 years. The change in Japan’s postwar fertility is analysed using formal demographic tools such as parity progression ratios and decomposition methods. The analytical results show that before the oil crisis of 1973, the reduction in marital fertility played a dominant role, while the delayed timing of marriage has been a principal factor since the mid-1970s. The delayed timing of first and second births has also played a relatively important role in determining actual fertility levels in the 1990s. The paper examines various socio-economic factors contributing to these demographic shifts over time in postwar Japan. A number of policies and programs implemented over the past decade by the Japanese government to boost fertility are briefly described, together with their limitations.