Measuring change and continuity in parity distributions

Procedures are developed to allocate the change in mean fertility to the change in specific parities or groups of parities. One procedure uses the proportion at each parity and another uses parity progression ratios. Both are based on the delta method for approximating change in a function of several variables. Drawing on an analogy to survival in a life table, the relational logit model is applied to parity progression. This method allows several parity distributions to be synthesized and to have differences summarized with two parameters. The three procedures are applied to successive cohorts of white U.S. women who completed their childbearing between 1920 and 1980.     

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)     

A decomposition of trends in the nonmarital fertility ratios of blacks and whites in the united states, 1960–1992*

We use a method of standardization and decomposition developed by Das Gupta to update Smith and Cutright’s analysis of demographic factors responsible for increases in the nonmarital fertility ratio (illegitimacy ratio) among blacks and whites in the United States. We create standardized rates for each year between 1960 and 1992, and consistent, exhaustive decompositions of the nonmarital fertility ratio for any interval during this period in terms of four components: (1) the age distribution of women of reproductive age, (2) the proportion of women unmarried at each age, (3) the age-specific birth rates of married women, and (4) the age-specific birth rates of unmarried women. Nonmarital fertility ratios are much higher among blacks than among whites, but both increased monotonically from 1960 to 1992. During the last 10 years, each increased by nearly 10 percentage points. Increases in the proportion of women not married, at all ages, account for the preponderance of the increase in black nonmarital fertility ratios. Increasing rates of unmarried childbearing, however, have played a role during the most recent decade (1983–1992). For whites, from 1960 until 1975, declines in marital fertility were most important in producing increases in the proportion of children born out of wedlock. Since then, these proportions have increased primarily because of increases in unmarried women s birth rates, and secondarily because of declines in the proportion of women who are married. These trends are consistent with arguments that emphasize declining economic incentives to marry and reduced access to, and acceptability of, abortion.     

Statistical modeling of selected aspects of the childbearing process with application to world fertility survey countries∗

The childbearing process should be monitored in developing countries experiencing high population growth rates and high levels of maternal and infant mortality. A mathematical model for estimation of certain aspects of the childbearing process, which requires only data on age‐specific fertility rates, is developed. Synthetic maternal childbearing indices, namely, mean ages at first and last birth, length of reproductive life span, inter‐birth spacing, and proportion of childless women, in addition to the well‐known mean age at childbearing, for the WFS countries are obtained using the proposed model. The indices are free from age truncation effects, and, under certain assumptions, provide information about a cohort's completed fertility before the women stop reproducing. The effects of women's residence and education on fertility are also examined.     

Statistical modeling of selected aspects of the childbearing process with application to World Fertility Survey countries

"A mathematical model for estimation of certain aspects of the childbearing process, which requires only data on age-specific fertility rates, is developed. Synthetic maternal childbearing indices, namely, mean ages at first and last birth, length of reproductive life span, inter-birth spacing, and proportion of childless women, in addition to the well-known mean age at childbearing, for the WFS [World Fertility Surveys conducted in developing] countries are obtained using the proposed model. The indices are free from age truncation effects, and, under certain assumptions, provide information about a cohort's completed fertility before the women stop reproducing. The effects of women's residence and education on fertility are also examined." (SUMMARY IN FRE)     

Intensive Parenting: Fertility and Breastfeeding Duration in the United States

Using 30 years of longitudinal data from a nationally representative cohort of women, we study the association between breastfeeding duration and completed fertility, fertility expectations, and birth spacing. We find that women who breastfeed their first child for five months or longer are a distinct group. They have more children overall and higher odds of having three or more children rather than two, compared with women who breastfeed for shorter durations or not at all. Expected fertility is associated with initiating breastfeeding but not with how long mothers breastfeed. Thus, women who breastfeed longer do not differ significantly from other breastfeeding women in their early fertility expectations. Rather, across the life course, these women achieve and even exceed their earlier fertility expectations. Women who breastfeed for shorter durations (1–21 weeks) are more likely to fall short of their expected fertility than to achieve or exceed their expectations, and they are significantly less likely than women who breastfeed for longer durations (≥22 weeks) to exceed their expected fertility. In contrast, women who breastfeed longer are as likely to exceed as to achieve their earlier expectations, and the difference between their probability of falling short versus exceeding their fertility expectations is relatively small and at the boundary of statistical significance (p = .096). These differences in fertility are not explained by differences in personal and family resources, including family income or labor market attachment. Our findings suggest that breastfeeding duration may serve as a proxy for identifying a distinct approach to parenting. Women who breastfeed longer have reproductive patterns quite different than their socioeconomic position would predict. They both have more children and invest more time in those children.     

American Family Building Strategies in 1900: Stopping or Spacing

Contemporary populations frequently space the births of children, and also attempt to stop childbearing after achieving a desired family size. While stopping behavior was evident in European populations in the late nineteenth century, little is known about the degree to which they attempted to space their children at specific interval lengths. This paper compares spacing patterns among various groups of white U.S. women in 1900, who were distinguished by varying family sizes and levels of fertility control. On the whole, there is little evidence of childspacing differences among native white populations, except for some very low parity women. The findings support the continued analysis of age patterns of fertility as the major means for determining the onset of conscious family limitation.     

Parity-specific fertility intentions and uncertainty: the United States, 1970 to 1976

A theoretical and analytic model of fertility intentions is proposed which treats “don’t know” responses and other uncertain responses as distinct from more firm intentions. Methodologically, these analyses show that “don’t know” responses need not be treated as missing data, but instead are both valid and meaningful responses. Furthermore, eliminating these uncertain respondents would have the negative effects of distorting across survey comparisons in intentions due to shifts in aggregate uncertainty, reducing the likelihood of accurately detecting shifts in fertility intentions, and lessening the representatives of the sample analyzed. Substantively, in conjunction with Morgan (1981), these results show that the sharp 1965–76 decline in the likelihood of intending more births at parities 2 through 5 occurred as women halted childbearing at minimal acceptable levels and postponed further childbearing. With time (or age), this delayed fertility became fertility about which the respondent was uncertain and, finally, fertility foregone. Since 1970, similar shifts are observed at parities 0 and 1, perhaps foreshadowing an increase in voluntary childlessness and one-child families.     

International Migration, Sex Ratios, and the Socioeconomic Outcomes of Nonmigrant Mexican Women

This article assesses whether international migration from Mexico affects the marital, fertility, schooling, and employment outcomes of the Mexican women who remain behind by exploiting variation over time as well as across Mexican states in the demographic imbalance between men and women. I construct a gauge of the relative supply of men for women of different age groups based on state-level male and female population counts and the empirically observed propensity of men of specific ages to marry women of specific ages. Using Mexican census data from 1960 through 2000, I estimate a series of models in which the dependent variable is the intercensus change in an average outcome for Mexican women measured by state and for specific age groups, and the key explanatory variable is the change in the relative supply of men to women in that state/age group. I find that the declining relative supply of males positively and significantly affects the proportion of women who have never been married as well as the proportion of women who have never had a child. In addition, states experiencing the largest declines in the relative supply of men also experience relatively large increases in female educational attainment and female employment rates. However, I find little evidence that women who do marry match to men who are younger or less educated than themselves.     

The impact of child care on fertility in urban Thailand

Women’s labor force participation in Thailand, particularly in the modem sector, recently has increased in conjunction with rapid declines in fertility. This paper examines whether a relationship exists between child care considerations and fertility decision making among Bangkok women. Although the two-child family has become the norm in recent years, and although most respondents said that ideally they would like to have two children, a high proportion of women surveyed said they planned to only have one child. Women’s work status and type of employment is found to strongly affect the likelihood of having a second birth: those who work at jobs that not only are low-paying but are located in a formal setting are least likely to have a second child. The type of child care for the first child also has an impact: those whose first child is in a less preferred situation are less likely to have a second. Variables measuring the need for and type of child care are found to have greater consequences for fertility than do usual measures of socioeconomic status.     

Fertility of Australian birth cohorts: Components and differentials

The paper examines the change in the level and pattern of fertility that took place in the post-1971 period, and the downward completed fertility of successive generations of Australian women born since 1933–37. The change in cohort fertility is assessed in terms of the cohort parity progression ratios, and the four components of cohort total fertility: the proportion of women who proceeded to have a birth, mean age at first birth, mean age at last birth, and average interbirth interval for women who had at least two births. The other aspects discussed are the cohort fertility differentials and the implications of the current trends for future fertility in Australia.     

An Econometric Investigation of Easterlin's ‘Synthesis Framework’: The Philippines and the United States

In this paper we estimate a fertility model based on Easterlin's synthesis framework. The model assumes that not all couples are able to achieve their desired number of living children because of supply constraints and that, for other couples, the number of living children may exceed desired fertility, depending upon child mortality, the level of fertility in the absence of control, and the degree of contraceptive regulation practised. Estimates of the model for samples of women with completed fertility taken from the Philippines (1973) and the United States (1965) indicated that a higher proportion of Filipino women than women in the U.S. were unable to achieve desired fertility because of supply constraints, that levels of fertility control of Filipino women not supply-constrained were lower, and that excess fertility of Filipino women was much higher. Demand-for-children equations based on the constraints model were quite different from those not taking into account the possibility that some women were supply-constrained, or that some women may have had more children than desired.     

Changes in fertility in Japan by region: 1920–1965

Changes in fertility for the 46 prefectures of Japan are traced from 1920 to 1965, using census and vital statistics. During the period, substantial declines were recorded in both marital-fertility levels and the proportions of women of childbearing age who were married. Regional variation is pronounced in the timing of the onset of the decline in marital fertility. Only in the most industrialized districts did marital fertility begin to fall before 1950; thereafter, sharp declines were recorded in all parts of Japan. The marriage proportion, in contrast, was falling rather steadily throughout the islands between 1920 and 1950, after which the proportion stabilized. The decline in overall fertility that occurred before 1950was caused, then, primarily by a reduction in the proportion married; only after 1950 did a decline in marital fertility become a. major factor. The time pattern of change in marital-fertility levels and proportions married for Japan differs from that observed in western Europe, where low proportions married are recorded in the earliest national censuses. Apparently a fall in proportions married in western Europe preceded by one or two centuries the major sustained declines in marital fertility that were part of the so-called demographic transition.     

Fertility Decline,Girls’ Well-being,and Gender Gaps in Children’s Well-being in Poor Countries

The influences of recent dramatic declines in fertility on girls’ and boys’ well-being in poorer countries are understudied. In panels of 67–75 poorer countries, using 152–185 Demographic and Health Surveys spanning 1985–2008, we examined how declining total fertility and women’s increasing median age at first birth were associated with changes in girls’ well-being and gender gaps in children’s well-being, as reflected in their survival, nutrition, and access to preventive healthcare. In adjusted random-effects models, these changes in fertility were associated with gains in girls’ survival at ages 1–4 years, vaccination coverage at ages 12–23 months, and nutrition at 0–36 months (for women’s later first childbearing). Declining total fertility was associated with similar gains for boys and girls with respect to vaccination coverage but intensified gender gaps in mortality at ages 1–4 years and malnutrition at ages 0–36 months, especially in higher-son-preference populations. Later increases in women’s median age at first birth—reflecting more equitable gender norms—were associated with declines in these gaps. Promoting equitable investments in children through family planning programs in higher-fertility societies is warranted.     

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

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

A probability mixture model of completed parity

This research was designed to find a probability model that would adequately describe completed parity for women in populations characterized by high fertility combined with high zero parity. A negative binomial mixture distribution was adapted for this purpose. The form of this distribution suggests the hypothesis that human populations consist of two subgroups of women with respect to completed parity, defined according to whether they do or do not produce viable offspring. Results of the present research further suggest that the proposed distribution for completed parity has general applicability across human populations, whether they are of a high or low fertility type, and whether they have a high or low zero parity.     

The TFR and birth control]

Total fertility rate if (TFR) is a simple an straight forward measure of women's fertility. However, it is difficult to use the TFR as a target measure in FP programs. If TFR level is set as a target for a particular year, how can women's fertility be regulated to achieve this target? The following analysis suggests a simple model to control the proportion of birth parity. First, the TFR is decomposed into a parity- specific TFR. The parity-specific TFR can be worked out using coefficients of the regression models calculated from data of previous fertility surveys. Once the TFR is given, the parity-specific total fertility can be calculated using a model with coefficients from empirical data. Then the number of births of each parity may be calculated from the parity-specific TFR using the female age structure in a particular year, the survival probability, and the standard fertility model for each parity. When the number of surviving children of each women at child-bearing age is known, the desired proportion of births of each parity can be calculated using the standard birth probability during a years. From these models, it would be possible to calculate how many women can have their first child/year, and how many can have the second. Thus, family planning organizations would be in a position to formulate a birth quota on the basis of the above information.     

Parental age and offspring mortality: Negative effects of reproductive ageing may be counterbalanced by secular increases in longevity

As parental ages at birth continue to rise, concerns about the effects of fertility postponement on offspring are increasing. Due to reproductive ageing, advanced parental ages have been associated with negative health outcomes for offspring, including decreased longevity. The literature, however, has neglected to examine the potential benefits of being born at a later date. Secular declines in mortality mean that later birth cohorts are living longer. We analyse mortality over ages 30–74 among 1.9 million Swedish men and women born 1938–60, and use a sibling comparison design that accounts for all time-invariant factors shared by the siblings. When incorporating cohort improvements in mortality, we find that those born to older mothers do not suffer any significant mortality disadvantage, and that those born to older fathers have lower mortality. These findings are likely to be explained by secular declines in mortality counterbalancing the negative effects of reproductive ageing.     

Fertility trends in Australia

Using published data from the Australian vital registration and census systems, several time series are compiled: crude birth rates from the 1860s; fertility rates from the 1880s; age-specific and parity-specific measures from the 191Os; cumulative fertility measures by birth year of parent beginning with the 1890s; and cumulative fertility measures for marriages by year contracted from the 1910s.The decline in fertility to the 1930s, the upswing to 1961, and declines thereafter revealed by annual fertility measures show far more variation than do measures of total generation fertility—2.7 children per woman born in 1893–95, 2.3 1906–10, 2.8 1921–25, and perhaps 3.0 for women born in the 1930s. Both annual and generation measures show a younger age at parenthood, a decrease in childlessness, and progressively fewer large families. In the light of present experience, it seems not unreasonable to project generation fertility of 2.5 children, implying a crude birth rate of about 20 per thousand for the next fifteen years or so.     

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.