Patterns underlying fertility schedules: A decomposition by both age and marriage duration

Summary Model fertility schedules based on the proportions married and the age pattern of marital fertility are unsatisfactory to the extent that marital fertility does not depend on age alone but also on other factors. Most notably, models based just on age fail to allow for differences between populations in their composition by marriage duration. Examination of the major series of fertility rates specific by both age and duration of marriage (Sweden 1911-70, England and Wales, 1941-70) reveals striking underlying regularities. The marital fertility rates observed at any given point in time can be factored into three independent components - an overall level, a vector of age effects common to all marriage durations and a vector of duration effects common to all age groups. A simple product of these three components is shown to approximate the data very closely over the entire series, despite major changes in the aggregate levels of fertility and nuptiality during the periods concerned. Not only are the data tightly structured, conforming very closely to this simple multiplicative model, but the vectors of age and duration effects themselves are shown to exhibit clear and meaningful regularities.     

Intermediate fertility variables and marital fertility rates

Summary Using relatively simple mathematical techniques, an analysis is made of a comprehensive reproductive model that describes the relationships between a set of intermediate fertility variables and the marital fertility rate. Two types of intermediate fertility variables are distinguished: (1) biological parameters and (2) control variables. A homogeneous model is outlined first. Next, this version is extended to include heterogeneity with respect to fecundability and coital rates. Tests of the model with data from two historical populations (i.e. Crulai, 1674-1742, and Tourouvre au Perche, 1665-1765) demonstrate that the model is, indeed, consistent with observed reproductive behaviour in actual populations.     

Fertility of the american negro in 1830 and 1850

Abstract A comparison of the proportionate age distributions for negroes enumerated in the decennial censuses of the United States in the first half of the rorh century indicates that by 1850, negro fertility apparently had been declining for at least 20 years. This paper develops the relationship of the age distribution of a declining fertility population, where the decline has persisted for less than 25 years, to the stable population with the same current schedules of fertility and mortality. This relationship is used to estimate the negro birth rate and total fertility as of 1850. In turn, these estimates and the relationship of the age distributions of two stable populations with different fertility are used to estimate the negro birth rate and total fertility as of 1830.     

Explaining fertility transitions

In this essay. I suggest that the crisis in our understanding of fertility transitions is more apparent than real. Although most existing theories of fertility transition have been partially or wholly discredited, this reflects a tendency to assume that all fertility transitions share one or two causes, to ignore mortality decline as a precondition for fertility decline, to assume that pretransitional fertility is wholly governed by social constraints rather than by individual decision-making. and to test ideas on a decadal time scale. I end the essay by suggesting a perceptual. interactive approach to explaining fertility transitions that is closely allied to existing theories but focuses on conditions that lead couples to switch from postnatal to prenatal controls on family size.     

Measuring fertility norms

We argue that social norms must be measured at the group level of analysis, allow for a range of acceptable behaviors, and be linked to the individual level of analysis to explain social behavior. From a survey of young adults in Wisconsin (1973), we generated measures of family size norms from sibship experience and friends' expected family size. These measures satisfied our primary criterion for a social norm: Those with non-normative family size desires tended to shift expectations toward the norm. The analyses demonstrate the difficulty of estimating normative effects when by its very definition a norm is expected to restrict variation in human behavior.Revision of a paper presented at the annual meetings of the American Sociological Association, New York, New York, August 30–September 3, 1986. This research was supported by Grant 1-R01-HD-17190 and by Center Grant HD05876 from the Center for Population Research, NICHHD. Paula Goldman's work was supported by Training Grant 5732HD07014 from the same source.     

Measuring fertility demand

We propose a multidimensional conceptualization of fertility demand and evaluate potential measures of each dimension, using data from a telephone survey of Wisconsin residents age 18-34. Most of the measures met tests for interval-level measurement; all produced high estimates of test-retest reliability. We found support for only two dimensions of demand, intensity and certainty; potential measures of centrality had relatively low associations with any of the latent dimensions. Demand certainty improved prediction of fertility expectations beyond a trichotomous (yes, no, don’t know) measure, but demand intensity did not. We found mixed evidence for the conceptualization of fertility demand as a single continuum on which desire to avoid pregnancy is the opposite of desire to have a child.     

Nineteenth-Century fertility oscillations

Abstract A model of delayed response, developed within the frame of a general sociological analysis, is applied to oscillations in aggregate legitimate fertility, considered as delayed responses to variations in the marriage rate. The appropriate lag function is derived on the basis of an assumed fertility schedule by duration of marriage. It is shown that if oscillations were caused solely by marriage fluctuations they would be very smooth with an 'average period' of 25 years and upwards. In Swedish data from the period 1830-1879 this smooth pattern is discernible as one component, overlaid by short-term fluctuations for which some other cause must be found. After a discussion of alternative explanations it is submitted that the cause is the practice of birth control on a fairly extensive scale, long before the secular decline in marital fertility, a conclusion which ties in with the results of earlier analyses of nineteenth-century fertility.     

The influence of first generation fertility and economic status on second generation fertility

This paper examines the impact of parental economic status and family size on the actual and expected fertility of adult children using longitudinal data from two generations of families participating in the Panel Study of Income Dynamics. There was a modest positive relationship between first generation family size and second generation fertility. More importantly, the ideal family size of the parental family was more closely related to fertility behavior and plans in the second generation than was actual parental family size. In addition, the data revealed the hypothesized negative correlation between parental financial status and second generation fertility behavior and plans. Several mechanisms which could produce the correlation between parental characteristics and the fertility of their children are explored.The analysis reported in this paper was supported by Contract NO1-HD-42856 from the National Institute for Child Health and Human Development, Center for Population Research. Dr. Thornton is affiliated with the Survey Research Center, Institute for Social Research, University of Michigan, Ann Arbor, MI 48106. Requests for reprints should be directed to him.     

A method for comparative analysis of fertility dynamics represented by sequences of fertility schedules

A method to compare fertility sequences, each of which represents a cyclical fluctuation around an underlying trend, is presented. Each fertility sequence is viewed as composed of a time trend in childspacing pattern and a corresponding trend in terminal fertility rate. The procedure involved in comparing each component of one fertility sequence with the corresponding component of another is described and illustrated. Using hypothetical data it is shown, among other things, that ifA andB are two cyclical fluctuations in fertility such that (i) the cycles in both are of the same length, (ii) the terminal fertility components of the two are identical, and (iii) the trend in the mean age at childbirth associated withA is higher than the corresponding trend associated withB, then, replacingB withA need not necessarily result in lowering the long-run rates of increase in the birth sequence.     

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.     

The fertility of two-generation urbanites

In this paper it is argued that in studies of urban fertility, the relationship between socio-economic variables and fertility has been obscured by the presence of rural migrants in the populations under investigation. Accordingly, data obtained from families of completed fertility in six probability samples of metropolitan Detroit are divided into two groups, farm migrants and two-generation urbanites.

In general, the socio-economic differences in fertility observed among the “pure” urban types in Detroit are found to be small and inconsistent, most of them being statistically insignificant. The inverse fertility pattern found in the total Detroit population is attributed to : (a) the overrepresentation of farm migrants (who have high fertility) in the lowest social and economic positions in the city, and (b) the pronounced inverse pattern of fertility among the farm migrants.

It is suggested that the absence of an inverse fertility pattern among twogeneration urbanites and its presence among the farm migrants can be attributed to differences in family organization.     

The prediction of completed fertility

There has been considerable interest in the relation between familysize desires and completed fertility. Longitudinal data from the Princeton Fertility Study provide a unique opportunity to compare the number of children desired after the birth of a second child to the size of completed families. The average number of children desired by women after the birth of their second child predicts very well the average size of their completed families. The average family size desired at the first interview and average estimated completed family size some eight years later are identical for the total sample, and vary hardly at all within religious or education subgroups. One-third of the variance in the completed fertility of couples is "explained" by wife's family-size desires and the proportion of explained variance increases to two-fifths when we include the husband's first interview desires and the interval between marriage and second birth. Yet in spite of the relatively high correlation between desires and achievement, only 41 percent of these women achieved exactly the number of children they desired at the first interview, while 14 percent had two children more or fewer than originally desired. Nevertheless, data on contraceptive efficiency indicate that desires after the birth of the second child constitute meaningful goals in terms of which the respondents regulate their subsequent behavior-efficacy of contraceptive practice shows substantial improvement after the desired number has been achieved.     

Intergenerational patterns of teenage fertility

One of the frequently cited consequences of teen childbearing is the repetition of early births across generations, which thereby perpetuates a cycle of poverty and disadvantage. We use data from the 1988 National Survey of Family Growth (NSFG), Cycle IV, to examine trends and determinants of the intergenerational teen fertility link for women who reached adolescence between the 1950s and the 1980s. We find that daughters of both white and black teen mothers face significantly higher risks of teen childbearing than daughters of older mothers. We also find, more generally, that patterns of teenage family formation (i.e., both marriage and childbearing behaviors) tend to be repeated intergenerationally. The results suggest that the intrafamily propensity for early childbearing is not inherited biologically, at least not through factors related to the timing of puberty. Rather, the intergenerational patterns appear to operate at least in part through the socioeconomic and family context in which children grow up.     

Economic development and fertility

Two schools of theorists have been concerned with the effect of economic development on fertility. One school has contended that economic development has an inhibiting effect on fertility. The demographic transition which has occurred among the non-developed countries confirms their viewpoint. Another school of thought, including in its members Thomas Malthus, has believed that economic development promoted fertility. Much empirical evidence may also be brought to bear to support this viewpoint.The present paper attempts to reconcile these viewpoints. It is hypothesized that the direct effect of economic development is to increase fertility. However, various factors which usually accompany the process of economic development serve to reduce fertility. These include an increase in the level of education and a reduction in infant and childhood mortality. Making use of data for 41 nations pertaining to the decade of the 1950's, it is found that fertility is directly associated with per capita net national product when controls for other relevant variables are in8tituted. On the other hand, per capita newspaper circulation is inversely related to fertility, and infant mortality is directly related.If the hypothesis advanced in this paper is correct, relatively large governmental expenditures on health and education will enhance the reduction in fertility obtainable from an increase in national economic level alone.     

Hyperbolic discounting and fertility

This paper analyzes the impact of hyperbolic discounting on the timing and on the number of births. Using a simple three-period model, it shows that, without the opportunity to shift the burden of rearing children into the future, hyperbolic discounters will give birth to fewer children. If child-care costs can be shifted completely to later periods, the impact of hyperbolic discounting on births depends on the underlying motive for motherhood, namely, whether children are regarded as consumption or investment goods. A large-sample empirical analysis, which uses an inconsistent savings pattern as an indicator of time inconsistency, confirms the theoretical results.