The pattern of reproductive life in a Berber population of morocco

Abstract

Reproductive patterns were studied from data collected in 1,450 Berber households in the province of Marrakesh, Morocco in 1984. Women aged 45–49 years had a mean of 8.9 pregnancies to achieve 5.7 living children. Social influences on fertility rates show the importance of tradition, particularly through time‐dependent variables such as age at marriage, waiting time to first birth, interbirth intervals, and duration of breastfeeding. Birth control does not appear to affect the tempo of fertility; rather, its main use is to bring the reproductive period to a close. The comparison of two subsamples of women separated by a 25‐year interval indicates an actual acceleration of the tempo of fertility by the reduction of waiting time to first birth and of interbirth intervals. The supposed ongoing process of demographic transition is not clearly observed in this population.     

A regression approach to the projection of U.S. fertility based on past fertility data

Abstract

The method of fertility projection used by the U.S. Bureau of the Census involves assumptions about the ultimate cohort total fertility rate and the ultimate cohort mean age at childbearing based on recent levels of fertility and women's birth expectations. This paper provides an outline of a general regression approach to fertility projection based on past data which would generate these two ultimate cohort characteristics. The technique is illustrated by using the U.S. single‐year age‐specific fertility rates up to 1986 for total women and projecting them indefinitely into the future until they become stable for both calendar years and cohorts.     

Changes in Sibling configurations for American preschool children

Abstract

This paper uses data drawn from the 1940 through 1980 Public Use Microdata Samples of the U.S. Census of Population to document sibling configurations from the child's perspective. Changes in four aspects of siblings are examined for five cohorts of white and black preschool‐aged children: number, birth order distributions, spacing intervals, and sex composition. Changes in fertility behavior of adults in the post‐war era had a profound effect on the structure of sibling systems experienced by children. Successive cohorts of preschool children show a rise in number of siblings through the early post‐war years before showing sharp declines in number of siblings through the 1960's and 1970's. These shifts in size of sibling sets are reflected in changes in the proportion of each cohorts who are first born and only children, both of which have increased substantially by the 1980 cohort. The 1940 and 1980 cohorts have similar proportions of children with short intervals. However, the middle cohorts show the effects of the quickened pace of fertility with substantial proportions of children with comparatively short birth intervals. Finally, substantial shifts across cohorts in several measures of sex composition of children are observed. Most significantly, there is a marked decline in the proportion of children experiencing an opposite‐sex older sibling.     

Evidence of increasing natural fertility in Taiwan

Abstract

A comparison of the age‐specific marital fertility experience of three successive cohorts in Taiwan indicates that the later cohorts have experienced progressively higher rates of natural fertility at each age from 15–19 to 35–39. Their fecundability is correspondingly higher and post‐partum sterility, shorter. These changes in natural fertility levels occurred almost simultaneously with recorded changes in health and nutrition levels. These findings support the hypothesis that during the process of modernization and the fertility transition, the level of natural fertility increases, potentially as a result of improvements in health and nutrition, and changes in lactation practices. It is the net effect of increases in natural fertility on the one hand and deliberate fertility regulation on the other, that determines the course of fertility over time, especially at early stages of modernization and the fertility transition.     

A period analysis of parity distribution among white and nonwhite women in the United States, 1940–1974

Abstract

The historical trends of childlessness and of one‐child, two‐child, and three‐or‐more‐child families among white and nonwhite women in the United States are studied in terms of period fertility tables. Given the age and parity of a woman, we can read from the fertility tables how her parity is expected to change at successive ages during the rest of her childbearing period, if she is subjected to the age‐parity‐specific fertility rates for a particular year. The fertility tables for white and nonwhite women are constructed for the years 1940, 19S0, 1960, 1970, and 1974. These tables show that among white women who have completed their childbearing (with period rates), the percentage with more than two children has decreased from 66 in 1960 to 27 in 1974, whereas the corresponding reduction among nonwhite women is from 67 to 48 per cent (Table 1, Case 1).     

More on the determinants of the fertility transition

Abstract

The economic approach to fertility is an application of the economics theory of consumer behavior. It is assumed that consumers of children are utility‐maximizers with stable preferences over time. Thus, changes in fertility are related to changes in household income and the “price” of children. One concern in this approach is that demographic changes are a product of changes in tastes rather than exogenous changes in economic factors such as the earning ability of women. In this paper, the effect of economic variables on the demand for children in the United States in 1950, 1960, 1970, and 1980 is examined. Support is provided for the hypothesis that the earning ability of women is an important determinant of fertility.     

Selection intensities in mothers of twins and in mothers of singletons

Abstract

Opportunity for selection was assessed in a group of mothers with twins and was compared with estimates obtained in mothers who gave birth to singletons only from the same population. Both groups were matched on a number of confounding variables in the framework of a case/control methodology. Two time periods involving demographic changes were studied separately. After appropriate adjustment for the increased family size of mothers of twins, results show that selection intensities are greater in twin‐bearing mothers than in controls. The fertility component of the selection index is lower than that of mortality if childless women are taken into account. However, the index of opportunity for selection is rather low by current standards but, given the methodology used, should reflect genetic rather than environmental selection. Notwithstanding, it would be difficult to explain the recent change in the twinning rates in the population by the actual level of selection indices.     

In memoriam: Maurice A. Bigelow

Abstract

Interracial children of white mothers and black fathers were compared to interracial children of black mothers and white fathers on growth rates during the first year of life. Results indicate that interracial children of white mothers gained less weight between birth and four months of age than did interracial children of black mothers or monoracial black or white children. By one year of age, catch‐up growth appears to have occurred, and there is little evidence for lasting effects of the growth retardation during the first four months of life.     

An examination of factors influencing black fertility decline in the Mississippi Delta, 1880–1930

Abstract

Although the fertility decline in the black population in the Mississippi Delta between the late 1870's and early 1930's closely paralleled that of the national black population, it rose much more dramatically in the 1940's and 1950's to almost 1880 levels. Given the especially rural and oppressed conditions of blacks there, the initial decline seems puzzling. Low fertility rates in the 1930's reflected a large proportion of childless females. Investigations of changing contraceptive usage and mate exposure suggest both were minor components at most. Several physiological impairments were investigated including dietary deficiences, malaria, tuberculosis, and sexually transmitted diseases (STD). Evidence suggests STD played the major role, facilitated by nutritional and other health problems. Models relying heavily on those developed by McFalls and McFalls (1984) suggest 50–80 percent of the decline could have been due to the spread of STD. Age‐specific birth rates for different periods and post‐World‐War‐II fertility increases seem consistent with this finding.     

Age at first birth and family size: Evidence from a longitudinal study

Abstract

This paper examines the correlates of the relationship of age at first birth to completed parity, using data from a fifteen‐year longitudinal study. Particular emphasis is given to measures of orientation toward family roles which have been singled out in previous studies as a likely causal factor not yet examined. Women who had an early first birth went on to have larger families than women who postponed childbearing longer. Demographic factors, including premarital pregnancies, unwanted births, and fecundity differentials, did not appear to account for the observed relationship. The hypothesis that early socialization toward traditional female roles might account for the higher fertility of women who began childbearing early was not confirmed. Women with a first birth at a young age were not characterized by more traditional sex‐role behavior or attitudes nor did they express higher initial fertility preferences. They did more often increase their fertility preferences over the inter‐survey period.     

Human fertility and land tenure in highland Bolivia

Abstract

Basic demographic data of landless and landed peasants from the highlands and valley of Northern Potosi, Bolivia, are compared. Household size and crude birth rates are larger in the highlands than in the valley. Within the highland population, no statistically significant difference was observed between the age‐specific fertility of landless and landed women, nor in the survivorship ratio of their offspring. The prevalence of exchange and reciprocity at the village level may be responsible for the absence of important differences in the fertility and mortality patterns of the landed and landless.     

Fertility at low and high altitude in central Nepal

Abstract

Data are reported on ages of menarche, first marriage and first childbirth, migration, venereal disease, birth control, birth spacing and on completed fertility rate in populations of Central Nepal living at low (8,500 feet) and high altitude (12,400 feet). The high‐altitude population reported a significantly lower completed fertility rate which could be partly accounted for by later age at marriage and first childbirth and increased birth spacing. Longer post‐partum ammenorhea and breast feeding did not account for the increased average pregnancy gap.     

Clinical implications of genetic susceptibility to diabetes mellitus

Abstract

Relatively little attention has been given to the interpretation of age‐at‐marriage differences in fertility. This paper discusses possible demographic and sociological sources of this differential. The argument is made that sociological interpretations deserve increased attention since most of the observed differential persists after control for likely demographic components (premarital pregnancy, unwanted fertility, and subfecundity) and for correlated social and background variables (education of self and parents, religion, farm background, number of siblings, whether respondent's parental family was intact, and husband's age at marriage). Multiple‐classification analysis is employed. The analysis concludes by noting that age at first birth has an even stronger relationship with fertility than age at marriage and that the sociological dimensions of age relevant to age at marriage are even more appropriate to age at entrance into motherhood.     

Identification of germinal disk region derived genes potentially involved in hen fertility

Despite the regular decrease in fertility observed in hens, especially in “meat” lines, little is known about genes affecting fertility. We used the Affymetrix microarray to search for oocyte genes whose expression would vary in relation to fertility rate in both “laying” and “meat” line hens. We focused on oocyte genes because several of them have been found to be involved in fertility in other species. Based on microarray analysis, 54 and 84 genes were differentially expressed between germinal disc regions (GDR) of F1 maturation stage oocytes from hens exhibiting either high (100%) or low (from 22% to 80%) fertility rate from laying and meat lines respectively. Most of these differentially expressed genes were distributed between “laying” and “meat” lines indicating that mechanisms involved in the decrease in fertility rates in these two cases were independent. Real time RT‐PCR performed on the same samples which were used for microarray confirmed in several cases differences in gene expression levels detected by microarray. Moreover the correlations between gene expression levels and fertility rates were evaluated for the 10 most interesting genes at different stages of follicular maturation and early embryo development on individual GDR samples from hens exhibiting different fertility rates. In total, we identified five genes whose expression levels correlated with fertility rate in accordance with findings of microarray analysis and real time RT‐PCR: VWC2, CR407412, TAPA, FGL2, and TRAP6. The biological significance of these genes sheds light on potential mechanisms influencing fertility and could provide candidates for fertility markers in the hen. Mol. Reprod. Dev. 76: 1043–1055, 2009. © 2009 Wiley‐Liss, Inc.     

The prospects for genetic improvement

Abstract

Recent versions of the economic theory of fertility have attempted to make the framework more generally applicable to all types of populations through an explicit treatment of supply considerations in combination with an analysis of the determinants of demand. Easterlin has suggested that the supply of children to an individual couple is determined by biological constraints in combination with the Davis‐Blake intermediate variables and with mortality patterns. However, anthropological studies of household structure, fertility, adoption, and migration point to a broader definition of the supply of children and to a more dynamic view of the ways in which supply and demand for household members are adjusted over the life‐cycle of the household.     

Selection intensities in menopausal and permanent contraceptor women of a rural population in India

Abstract

The opportunity for selection was estimated in the rural population of Visakhapat‐nam District, Andhra Pradesh, India. The index of total selection was found to be low. Selection in relation to birth control reveals that opportunity for selection is lower among the women who completed their fertility by family planning methods than in women who completed their fertility by attaining menopause. Further, the results showed that differential fertility and mortality make equal contributions to the total measure of selection in both groups.     

Natural selection and degenerative cardiovascular disease

Abstract

The analyses shown here indicate that the pervasiveness of fertility trends found earlier for the 1950's and 1960's has continued for the 1970's. The national period fertility trends have occurred within every racial, social, and economic subgroup examined. As before, there is no evidence of a narrowing of fertility differentials within successive cross‐sections. Variables, such as race or education, continue to exert effects on cross‐sectional fertility differences. Standard socioeconomic variables operate to shift the entire trend line up or down, but do not explain the trend line. The question remains of what causes changes in period fertility rates in developed societies.     

Economic and social correlates of infant mortality: A cross‐sectional and longitudinal analysis of 63 selected countries

Abstract

Genealogical records containing birth and death dates for completed families have been analyzed to compare the longevity of twins, sibs and parents. The data are restricted to twins and sibs who survived to adulthood and married. The findings, similar to those found with respect to fertility (Wyshak and White, 1969), show that twins, especially male twins, are disadvantaged in comparison with their male sibs. Sib‐sib and parent‐offspring correlation analysis confirmed that there is a genetic component in the determination of life span, but environmental factors contribute more to the total variation. No evidence of a stronger maternal than paternal effect was found. Twin bearers also lived longer than nontwin bearers. Even among persons who survived to age SO or more, parents of twins had more children and lived slightly longer than their twin and nontwin offspring. Regression analysis for persons who survived to SO or longer indicated that, in addition to life span of parents, secularity (year of death) and fertility (number of children borne) were the best predictors of longevity, though only a small proportion of the variation could be accounted for by these and other demographic variables. Life span has shown a consistent increase over time from the seventeenth century through the nineteenth century, while fertility has tended to decline. However, among persons surviving to age SO, when the relation between secularity and fertility and secularity and longevity is controlled, a significant correlation between fertility and longevity remains. This relation, observed in populations that did not practice voluntary family size limitation, would not be found in contemporary data. Maternal mortality accounted for the shorter life span of women than for men; eliminating its effect gives women a slight advantage. The fertility and longevity experience of migrants who survived to age SO is more favorable than that of persons who did not migrate.     

Assessing the correlates of desired family size in Shaanxi,China

Abstract

This exploratory analysis of factors associated with Chinese women's fertility desires uses data on married women between the ages of 18 and 35 who live in Shaanxi Province, China. Analyses using an economic framework found that both rural and urban couples who intended to sign, or who had already signed, the one‐child certificate reported wanting significantly fewer children. However, in rural areas (where 80 per cent of the provincial population lives), education level, living arrangements, participation in an arranged marriage, attitudes regarding the ideal age for marriage, and knowledge of the reasons for the government's fertility policies appear to play a relatively larger role in shaping fertility preferences.     

Fertility and patterns of labor force participation among married women

Abstract

Past research has shown that the labor market behavior of wives is discontinuous and affected by family events. Specifically, both cross‐sectional and panel data indicate that fertility decreases the period that a married woman spends working. Each birth appears to decrease labor force participation by one year or more. The present study attempts to specify these effects more completely. The variation in work patterns for each parity progression is examined to determine whether the fertility‐work effect is due to a few women who leave the labor force for an extended period during childbearing or due to a large number of women who have intermittent work histories. The analysis uses a national sample of women who were high school sophomores in 1955 and followed up as adults in 1970 and for whom retrospective data for each of the intervening years were obtained. Only married women with uncomplicated marital histories are included in the present study. We find dramatic evidence for two distinct types of response to childbearing. Women tend either to work almost continuously throughout the period or to drop out of the labor force for a very extended period of time after first birth.