Cumulative Fertility Research Articles

The impact of migration on fertility: an "own children" analysis for Thailand.

Abstract Reflecting a growing concern with high rates of urban growth in less developed countries, increasing attention focuses on the fertility of migrants to such places. The present study explores the relations between fertility, migration, and urbanization, using ‘own children’ data from the 1970 Census of Thailand. Information on ‘own children’ less than one year old is used to approximate fertility levels in the year before the census, and that on ‘own children’ aged 1–4 fertility levels during the four preceding years. Since migration was defined as a move to current residence between 1965 and 1970, the statistics on ‘own children’ less than five years old allow scrutiny of fertility during the period immediately before and after migration. Controlling for a variety of socio-economic characteristics of currently married women aged 20–49, and using several analytical approaches, the current fertility of migrants was consistently found to be higher than their own earlier fertility and higher than that of non-migrants in urban areas. Conversely, past fertility of migrants was lower than that of non-migrants, and past fertility levels of non-migrants were generally as high as current levels. The statistics thus suggest that migration is either selective of women with low fertility and/or that the migration process itself disrupts childbearing. Once the migrant women have moved, a ‘catch-up’ effect seems to operate to raise current fertility levels, but the cumulative fertility of migrants remains below that of non-migrants.

Socioeconomic Factors, Intermediate Variables and Fertility in Bangladesh

SummaryCumulative fertility as measured by deviation from the natural fertility schedule is determined more by intermediate variables such as child mortality, the use of supplementary food, lactation, and husband's absence, than by the practice of fertility control using modern contraceptive methods. Socioeconomic factors like education, urban residence and the possession of household assets, though differentiating these intermediate variables of fertility, do not have direct effects on cumulative fertility among the sample of Bangladeshi women in the Bangladesh Fertility Survey. The effect of age, controlling for the effect of these intermediate variables, remains strongly negative, suggesting an early onset of subfecundity. The implications of these findings for fertility trends and differentials in recent decades are discussed.

Differential fertility in Bangladesh: A path analysis

Previous studies of fertility in Bangladesh have mostly used crosstabular and multivariate analyses revealing the direct effect of selected socioeconomic and background variables. The indirect effects are relatively unknown. Analysis of data from the 1975-1976 Bangladesh Fertility Survey seeks to identify variables that significantly affect the cumulative fertility of both urban and rural women and to construct causal models to clarify the complex set of relationships. Path analysis is used on 8 variables: fertility index (number of children ever born to ever married women aged 9-49, age of wife (respondent), age at marriage, religion, childhood background of wife and husband, and educational attainment of both wife and husband. Data obtained from a sample of 4875 rural and 1403 urban women are used. Causal ordering of the variables began with the 4 exogenous variables: age, religion, and childhood backgrounds of the wife and husband. Education of husband and wife are placed next in sequence, followed by age at marriage and the fertility index. Path coefficients are estimated by applying ordinary least squares regression to the equations. "Children ever born" is regressed on all other variables for urban and rural areas. The 2 sets of coefficients are not equivalent and urban and rural data are analyzed separately. 13 paths are significant in the urban model and 11 in the rural model. The coefficients are small suggesting that other variables not included in the study effect fertility. In the urban model, 5 variables were found to have a statistically significant effect on fertility: age, religion, education for both husband and wife, and age at marriage. The indirect effect of religion operating through a network of compound paths suggests that Muslim affiliation tends to depress wife's and husband's education and age at marriage. Holding other variables constant, Muslim women tend to have more children than non-Muslim women. Wife's age at marriage negatively effects fertility. Wife's education has a negative effect on cumulative fertility, husband's education has a positive effect. Childhood backgrounds have insignificant effects, probably due to few childhoods being spent in urban areas; however, wife's childhood in an urban residence has a noticable effect through education and age at marriage. 3 variables in the rural model have significant direct effects: age, religon, and age at marriage. Religion's indirect effect through wife's education and age at marriage indicates that for Muslim women, education is lower, and hence age at marriage is lower and ultimately number of children ever born is higher. Wife's age at marriage has a negative direct effect. Neither wife's nor husband's education have a significant direct effect, unlike the urban model, probalby due to a relative lack of education in rural areas. The effects of religion in both models operate indirectly through age at marriage. Religion may affect fertility through other variables as well, e.g., perception of sexuality, preference for sons, contraceptives, and ritual abstinence. The positive effect of spouse's education in urban areas may be due to the effects of permanent household income and may reflect a lowering of the perceived financial burden of children, increased fecundity of his wife through improved nutrition and early weaning of children, decrease duration and frequency of occupational absences, and prevention of his wife from working outside the home. The negative effect of wife's education may be due to later marriage, increased independence, ability to accumulate resources for old age, and a desire to provide medical care for her children. These characteristics are likely to induce limited fertility through contraceptive usage. Given the universality of marriage, the tendency to marry at younger ages, and ineffective contraceptive practices, raising the age of marriage through governmental laws can lower fertility.

Response of Semiarid Grassland Sites to Nitrogen Fertilization: I. Plant Growth and Water Use

AbstractAlthough it has been repeatedly demonstrated that most perennial grassland ecosystems respond to N fertilization, knowledge of factors controlling N transformations involved in such responses is fragmentary. Eight rate‐of‐N‐fertilizer experiments were conducted for 5 or 6 years on established perennial grass sites near Mandan, North Dakota. Experiments were conducted within essentially the same precipitation and temperature regimes on sites differing in soil type, exposure, and grass species to determine their influence on N response. Above‐ground vegetation response to N fertilization depended primarily upon species — smooth bromegrass (Bromus inermis) was generally more responsive than crested wheatgrass (Agropyron desertorum) or native mixed prairie. No consistent patterns of root biomass response to N fertilization were obvious. At some sites or in certain years root biomass responses were fairly consistent, whereas at other sites or in other years, little response to N occurred. Water use efficiency (WUE) was greatest for bromegrass and least for native grasses, and was generally increased by N fertilization. WUE increased as aboveground growth increased, whether as a result of N fertilization or because of less evaporation at more protected sites. Cumulative dry matter response to N fertilization was highly correlated with cumulative fertilizer N added, with a different curvilinear relationships for each site.These results indicated that the magnitude of fertilizer N responses by perennial grasslands is site specific. Although the same general mechanisms seem to operate at the different sites, magnitude of response was controlled by the plant species present and by some soil type × location factors that are presently ill‐defined. These latter factors appear to influence the capacity of the soil to immobilize fertilizer N, capability of above‐ground plant growth to take up fertilizer N, and many other N transformations, and may be related to relative availability of water. Consequently interpretations of fertilizer experiments conducted on only one soil type or with only one species must be interpreted with caution.

Early Fertility and Lifetime Fertility

Teenage mothers are likely to have more children than those who postpone childbearing, but these differences are not as great as they used to be. There is also a pattern of convergence between black women and white women.

Intergenerational Occupational Mobility and Fertility: A Reassessment

This paper examines the relationship between intergenerational occupational mobility and family size: it focuses on the partition of cumulative fertility into 2 components -- intended and unintended births -- that may respond differently to social and economic sources of influence. 4 theoretical perspectives are drawn upon to set forth alternative predictions of the relationship between unintended and intended births for upwardly and downwardly mobile couples. The results of regression analysis of 1970 (U.S.) National Fertility Survey data lend support to Easterlins relative economic status hypothesis which advances the expectation of a positive relationship between direction of mobility and fertility although this pattern is observed only for unintended births. The implications of this finding for certain theories of fertility as well as for the inconclusive nature of previous research into the mobility/fertility relationship are discussed. (Authors)

Demographic variables and the recent trend in fertility in Guyana, 1960-1971.

Summary In Guyana during 1960–71, fertility declined not only among all women, but among all union status groups including married women, and also among both ethnic sub-groups, East Indians and non-East Indians. Discussion of the differing trends in cumulative and current fertility shows that the decline in fertility was very recent, dating from the mid-1960s, so that while cumulative fertility increased at older ages between 1960 and 1970, age-specific fertility declined at all ages between 1965 and 1971. Our examination of the intermediate variables leads us to conclude that motivationally determined variables were a more important cause of fertility decline than involuntary or biological factors. Involuntary factors actually had small positive effects on fertility, suggesting that the true fertility decline between 1960 and 1971 was even greater than observed. The relevant motivational variables fall into two groups, the union formation and the fertility control variables. The mean age at union formation rose by 0.89 years during these ten years, and this mainly affected the fertility of younger women (15-24). The effect of this factor was more complicated for older women: while more women had ever been in unions, and legal unions had increased at the expense of common-law unions, a lower proportion were currently in unions. The net effect of union status changes at older ages would have been to increase fertility. The fertility control variables, use of contraception, voluntary infecundity and abortion, were, however, responsible for fertility decline at older ages (25–44). These factors were particularly important in explaining the decline in marital fertility, since by definition the union-status factors do not apply to married women. The greater fertility decline of East Indian women reinforces our argument, because during the last 30 years this ethnic sub-group experienced greater social change than non-East Indians - their educational status improved more rapidly (though beginning from a lower base), and since they formed the major part of the agricultural labour force, it was East Indians who experienced most of the shift out of agriculture. These changes are all likely to raise the cost of children, and since fertility fell more rapidly in the group most affected, the evidence supports our explanation of fertility decline in the whole society.

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.

From One Generation to the Next: Changes in Fertility, Family Size Preferences, and Family Planning in an Indian State between 1951 and 1975

Over the last 25 years modernization in Karnataka, India, resulted in a large reduction in infant and child mortality, substantial increases in literacy, and initiation of an intensive family planning program. The drop in the birth rate during this period, however, was much less than would be anticipated under such circumstances. Two surveys carried out in 1951--52 and 1975 provide data on current and cumulative fertility, family size preferences, and knowledge and use of family planning. A comparison of these data leads to the conclusion that the level of family planning activities was not high enough to counteract the increase in the fertility of married women that was a consequence of modernization.

Structural determinants of childlessness: a nonrecursive analysis of 1970 U.S. rates.

Abstract This study tests two theories accounting for observed relationships between U.S. rates of childlessness and sociodemographic characteristics using data on Black and white women aged 30–44 from the 1970 U.S. census. Traditional theory sees the observed correlations as spuriously caused by involuntary sterility, while voluntaristic theory interprets the associations as evidence of influences on the decisions of fecund couples to remain childless. We examine the two positions by estimating and then comparing the aggregate causal structures of childless rates and cumulative fertility rates of women with proven fecundity. The traditional approach expects little if any relationship, while the voluntaristic approach predicts high similarity between the two estimated structures. Results support the voluntaristic position and thus offer indirect substantiation of the voluntaristic theory of areal variation in childless rates.

Labor Force Participation, Village Characteristics and Modernism and Their Influence on Fertility among Rural Thai Women.

Although lack of a significant relationship between areal characteristics and current fertility of rural Thai women may prompt the conclusion that fertility behavior is independent of their cultural environment this may be due either to the fact that the presence of modern characteristics was too recent to create an impact or to the failure of these indicators to effectively measure the degree of modernity of villages. With the general underlying hypothesis that the more modernized characteristics the village has the lower the fertility of village women and the higher proportion of village women practicing family planning village-level survey information attempted to relate the current and cumulative fertility of rural Thai women to 9 environmental variables felt to reflect modernity: 1) average village size; 2) average village distance from nearest health center; 3) average village distance from district office; 4) average number of radios per capita; 5) availability of television; 6) presence of primary school; 7) crude birth rate; 8) crude death rate; and 9) migration. Results were as follows: 1) none of the variables was found to be significantly related to fertility; 2) 3 variables average village distance crude birthrate and crude death rate were found to be significantly related to fertility and were monotonically related in an expected direction; and 3) a proportion of women currently practicing family planning was significantly related to village size average number of radios per capita and the 3 areal demographic variables. These findings will help to generate hypotheses which can form a basis for establishing linkages between socioeconomic change and fertility.

Target Fertility, Contraception, And Aggregate Rates: Toward A Formal Synthesis

This paper develops a stock adjustment model relating total expected births to conventional aggregate fertility rated for married women over 25. Each year, cohorts bear about 20 percent of their additional expected births. Aggregate U.S. rates have been consistent with expectations as expressed in surveys between 1955 and 1975; indeed, total expected births may be inferred from aggregate fertility behavior. A peculiar empirical finding is that the additional expected fertility of nonterminators has not changed since 1955, despite the dramatic decline in total expected and actual fertility. The model leads to a dynamic expression for the duration pattern of current and cumulative fertility and for the proportion of couples who have terminated childbearing. The model is also used to analyze the effects of changing contraceptive failure rates on fertility patterns. For example, a decline in "timing" failure rates increases duration-specific fertility five years later.

Religious Differentials in Fertility: Lebanon, 1971

Research has been conduted to determine define and explain the effects of religious affiliation on fertility with specific reference to a multireligious society. Data from the 1971 National Fertility and Family Planning Survey conducted by the Lebanon Family Planning Association have been evaluated and 2 major results have been found i.e. significant fertility differences do exist among Muslim and Christian sects and religious fertility differentials based on cumulative fertility are dependent on the level of socioeconomic status as measured by the wifes education. When education levels are low differentials are great; when education levels are high religious fertility differentials are negligible. These results suggest that religion may be an important characteristic in differentiating fertility behavior but only at certain socioeconomic levels. In countries where religious composition is a sensitive issue these results may have significant implications on population policymakers.

Religious differentials in fertility: Lebanon, 1971.

Summary The principal objects of this study are the description and explanation of the effects of religious affiliation on fertility in the multi-religious society of Lebanon. The data are derived from the 1971 National Fertility and Family Planning Survey which is the first probability sample ever taken of Lebanese couples with wives aged 15-49 years. The present inquiry yields two major results. First, significant fertility differences do exist among Muslims and among Christians. To speak of Muslim-Christian fertility differences is, therefore, misleading. Secondly, religious fertility differentials, based on cumulative fertility, are dependent on the level of wife's education. At low levels of wife's education, differentials are great; at high levels, religious differentials in fertility are insignificant. These findings are believed to be of importance not only to researchers concerned with religious fertility differentials, but also to those concerned with framing population policies in countries where religious composition is a sensitive matter.

Relative income and fertility

The present study examines the relationship between relative income (i.e., actual income in relation to the expected income of one's socioeconomic group) and fertility, using data collected by the 1967-1968 Canadian Family Growth Study (Balakrishnan et al., 1975). We broaden the tests of relative income beyond cumulative fertility to spacing behavior and then examine some of assumptions included in the relative income model of fertility. Results of the tests, in brief, are as follows: (a) Relative income is found to be more closely related to spacing than to cumulative fertility; and (b) the relationship between relative income and fertility is strongest among those couples who plan their life ahead and have a high level of education and occupation, and when temporal alignment is brought between the measures of relative income and fertility. For the relative income model to receive confirmation, it was specified that the following hypotheses must be confirmed: (a) that fertility behavior would vary positively with relative income but the fertility norm would show no relationship with relative income: and (b) that consumption norms and behavior would show no relationship with relative income. The outcome of these tests are in the expected direction, giving support to the relative income model. In addition, there is some evidence of predictive capability of the relative income model for correlative behavior.

The effect of child mortality experience on subsequent fertility: in Pakistan and Bangladesh

Summary This paper presents an empirical analysis of the effects, behavioural and biological, of child mortality experience on subsequent fertility in two South Asian Islamic nations. Data for the investigation came from retrospective pregnancy histories of 2,910 currently married women interviewed in the Pakistan National Impact Survey (1968-69) and from longitudinal vital registration data (1966-2070) of 5,236 women residing in a rural area of Bangladesh collected by the Cholera Research Laboratory. The aim of this study was to assess the importance of the child-replacement motivational response to child death experience after biological effects have been controlled adequately. A common approach employed previously has been to examine cumulative fertility according to child death experience. In Pakistan and Bangladesh, a consistently positive relationship was demonstrated between the number of children ever born and the number of child deaths. This method, however, did not exclude the inverse relationship, the influence of fertility on mortality, nor did it dissect out behavioural from biological effects. Utilizing a measure of subsequent fertility, live-birth-to-live-birth intervals, the study further illustrated another common pitfall. Since the risk of infant death, which leads to shorter birth intervals, is associated with the mother's reproductive history, women with child mortality experience are more likely to experience shorter intervals because of the biological effect of subsequent infant death. Behavioural influences may, therefore, be observed by considering only those birth intervals in which the first-born child survives to the end of the interval. With these limitations controlled, very few, if any, behavioural influences were noted in the Pakistan and Bangladesh data. Median birth intervals in Pakistan varied between 35-43 and 41-42 months, increasing with parity. Within each parity group, no consistent difference was observed between women with and without previous child loss. In Bangladesh, the median birth interval for all women with a surviving infant was 37-2 months. This was shortened to 24-31 months by an infant death. When intervals with infant deaths were excluded, little or no behavioural influence was detected among women of the same parity, but with varying levels of previous child loss. Even without behavioural effects, elimination of infant mortality in Bangladesh would reduce fertility by prolonging the average period of post-partum sterility. In the Bangladesh setting, however, the size of the effect was only about four per cent. This modest effect, more-over, was counterbalanced by an overall increase of net reproduction by seven per cent due to better survivorship of infants.

Demographic aspects of fertility in Thailand

Abstract Data from a national rural and urban sample survey are analysed in order to examine various demographic aspects of fertility in Thailand. Marital fertility rates found for Thailand are among the highest in Asia. Particularly noteworthy is the persistence of high fertility at older ages of childbearing for rural women. Cumulative fertility shows a pronounced relationship with age at marriage and current marital status. Women who marry at an older age or who experience disruption of their marriages are clearly more likely to have fewer children ever born. Differences in both current and cumulative fertility are strongly associated with residence. Rural women who constitute the vast majority of Thai women, experience the highest fertility, Bangkok-Thonburi women experience the lowest fertility and provincial urban women are characterized by an intermediate fertility level which is closer, however, to the experience of their counterparts in the capital than in the countryside. Rural-urban fertility differences are mitigated but by no means eliminated by differences in infant mortality. In both rural and urban areas a positive association between cumulative fertility and infant morality is evident. Breast-feeding, commonly practised for extended periods-among both rural and urban Thai women, undoubtedly serves to some extent as an intervening variable in this relationship. A comparison of current fertility with cumulative fertility strongly suggests that a decline in marital fertility has been under way recently among urban women, especially those residing in the capital, but not at all among rural women. Although it seems safe to assume that the urban fertility decline results in large part from an increasing use of contraception among urban women, those still in the reproductive ages who were using or had previously used birth control were characterized by higher cumulative fertility than women who had never practised contraception. Evidently couples resort to family planning only late in the family building process after they have already achieved or exceeded the number of children they wish to have.

Minority group status and fertility revisited.

This paper reexamines the effect of minority group status on fertility to discover the efficacy of two positions outlined by Goldscheider and Uhlenberg (1969) and Sly (1970). The problems raised focus on the definition of ethnic group, the failure to control for the effects of age at marriage and employment status of woman in fertility analyses, and the failure to examine current as well as cumulative fertility. Results tend to support Goldscheider and Uhlenberg's position that ethnicity has effects on fertility independent of other dimensions and point toward their recommendation that social psychological factors be examined to determine how fertility is influenced by ethnicity.

Evaluation of an experimental short interview form designed to collect fertility data: The case of Peru

Abstract A comparison is made of demographic data gathered using an experimental short interview form with that from the more traditional in-depth fertility and contraceptive KAP interview. The short form is weakest in measuring current fertility, somewhat more adequate in measuring cumulative fertility, and about equally as effective as the depth interview in measuring infant/child mortality. Most of the deficiency in the quality of the short-interview data can be attributed to accepting information from other household members or neighbors when the woman herself was not available.

Economic Analysis of Fertility in Israel: Point and Counterpoint

I view, in this paper, cross-section evidence on fertility in Israel through a very simple hypothesis based on the links among education, the cost of time of women, and the full price of children. The hypothesis is useful in explaining some aspects of behavior, but important facets of the variation in fertility remain unexplained. In recent years there have been several attempts to bring the determination of family size within the scope of the economics of household behavior (see Leibenstein 1957; Becker 1960; Mincer 1963; Easterlin 1968, 1969; Schultz 1969; and others). An economic theory of fertility starts with the postulate that hotuseholds maximize some utility function in which children and other goods appear as arguments subject to resource constraints in which the prices or the costs of production of the arguments appear. The effect of a change in any variable on the number of children depends on the extent to which it lifts the general resource constraint and induces an income effect and the extent to which it changes relative prices and induces a substitution effect. Recent developments in the theory of the household (particularly by Becker [1965] and Lancaster [1966]) provide a unified framework for handling various aspects of the fertility decision. However, in choosing