The Polygyny–Fertility Hypothesis: A Re-evaluation

Previous studies of the relationship between polygynous marriages and fertility have produced mixed results, although on balance evidence suggests that fertility levels are lower in polygynous than in monogamous marriages. It is argued that the inconsistent results stem from the aggregation of fertility data among all wives in polygynous unions, and that major differences are due to variations in fertility by wife-order and number of wives in polygynous unions. Data for 2534 polygynists with 7378 marriages are analysed and contrasted with fertility data from once married women, using information covering population of Utah during the nineteenth century. Our data indicate significant variations in fertility levels by wife-order; these fertility differences are largely due to variations in length of exposure to the risk of conception and birth intervals.     

Polygyny and the rate of population growth

Summary The roots, motives and feasibility of practising polygyny in societies with a balanced sex structure and the effect of polygyny on the rate of population growth are considered. High demand for labour combined with limited supply over the last several centuries, had been conducive to the evolution of a polygynous nuptiality pattern. The unprecedentedly high rates of population growth during the last several decades combined with progressive economic development have led to a change in the role of the labour factor and consequently diminished its impact upon polygyny. Polygyny is feasible because of a sex-age differential at first marriage, which enables younger cohorts of women to enter the marriage market, and thus results in a very early age at first marriage and universal incidence of marriage among women. A very young pattern of nuptiality inevitably evolves under polygyny, which tends to raise the rate of population growth. No significant variation in fertility between polygynous and monogamous women was found but substantial gaps in standards of living, child mortality, and educational attainment were noted for polygynous households. The findings imply that during the transition from polygyny to monogamy family size will tend to diminish, although initially fertility may not decline concurrently with changing socio-economic status. The most important effects on the rate of population growth thus result from the increase in age at first marriage and declining proportions of ever married women.     

Polygyny, Partnership Concurrency, and HIV Transmission in Sub-Saharan Africa

We study the relationship between polygyny and HIV infection using nationally representative survey data with linked serostatus information from 20 African countries. Our results indicate that junior wives in polygynous unions are more likely to be HIV positive than spouses of monogamous men, but also that HIV prevalence is lower in populations with more polygyny. With these results in mind, we investigate four explanations for the contrasting individual- and ecological-level associations. These relate to (1) the adverse selection of HIV-positive women into polygynous unions, (2) the sexual network structure characteristic of polygyny, (3) the relatively low coital frequency in conjugal dyads of polygynous marriages (coital dilution), and (4) the restricted access to sexual partners for younger men in populations where polygynous men presumably monopolize the women in their community (monopolizing polygynists). We find evidence for some of these mechanisms, and together they support the proposition that polygynous marriage systems impede the spread of HIV. We relate these results to the debate about partnership concurrency as a primary behavioral driver for the fast propagation of HIV in some parts of sub-Saharan Africa.     

Polygynists and Their Wives in Sub-Saharan Africa: An Analysis of Five Demographic and Health Surveys

Differential polygyny in Ghana, Kenya, Senegal, Uganda, and Zambia is investigated using individual-level Demographic and Health Surveys data. As well as contrasting polygynists' first wives with women in monogamous unions, the analysis distinguishes higher-order wives from first wives. This permits study of the determinants of the prevalence and intensity of polygyny respectively. Polygyny and other aspects of marriage interlock in very similar ways in all five countries. Individuals' experience of polygyny tends to reflect their luck in the marriage market rather than their socio-economic characteristics. While polygyny is less prevalent in urban areas, other socio-economic factors are important only in Kenya and Zambia, the two countries where less than 25 per cent of married women are in polygynous unions. The prevalence and intensity of polygyny are negatively associated. Thus, any drop in the prevalence of polygyny in Africa may be accompanied by a rise in the number of wives per polygynist.     

Polygyny as social and biological differentiation among Toposa agro-pastoralists of Southern Sudan

A demographic survey of eight Toposa villages in Southern Sudan was undertaken to delineate patterns of infant and childhood mortality. Among these predominantly egalitarian agro-pastoralists few standard socio-economic variables useful in the detection of demographic differentials were found. Instead, polygyny was used as a measure of social differentiation, hypothesizing that social differentiation induces demographic differences between polygynous and monogamous marriages. Analysis indicated social differentiation through gerontocracy, while significant differences in mortality and fertility levels were found berween monogamous and polygynous marriages, with the latter featuring higher fertility and mortality levels. Underlying rationale for these differences were sought through consideration of social and biological factors.     

Polygyny and child survival in Nigeria: Age-dependent effects

Mortality risks under age five are estimated using data from the 1990 Nigerian Demographic and Health Survey for children in monogamous and polygynous families. Integrating existing theories on polygyny’s relationship with infant and child mortality and some demographic concepts, the study shows that polygyny has different effects on infant and child mortality at different ages. The results indicate that polygyny does not have a significant effect on neonatal mortality (age less than one month). In contrast to the results of previous research, polygyny is significantly associated with lower child mortality during the post-neonatal period (1–11 months), but not during childhood (12–59 months). The study found socio-economic factors to be important confounders of the relationship between polygyny and mortality during the neonatal and post-neonatal periods. The protective effect of polygyny during the post-neonatal period suggests the need to further investigate circumstances that may favour post-neonatal child survival in polygynous families including availability of childcare.     

Polygyny and Fertility Among the Sereer of Senegal

The population laboratory of Ngayokhème, in Senegal, has been observed longitudinally since 1962. Information on marital status at the time of birth (rather than at the time of a survey) is used to examine the effect of polygyny on fertility. Although plural marriages are less fertile and the rank order of the wife has an effect, the mechanism appears to operate through the age difference of the spouses and the greater likelihood of temporary separate residence in the case of polygynous marriages. An examination of birth intervals suggests that the lower fecundity of older men, rather than a reduction of the frequency of intercourse, is the main factor. However, there is little relation between the fertility of different wives of the same polygynists.     

Polygynous Contexts,Family Structure,and Infant Mortality in Sub-Saharan Africa

Contextual characteristics influence infant mortality above and beyond family-level factors. The widespread practice of polygyny is one feature of many sub-Saharan African contexts that may be relevant to understanding patterns of infant mortality. Building on evidence that the prevalence of polygyny reflects broader economic, social, and cultural features and that it has implications for how families engage in the practice, we investigate whether and how the prevalence of polygyny (1) spills over to elevate infant mortality for all families, and (2) conditions the survival disadvantage for children living in polygynous families (i.e., compared with monogamous families). We use data from Demographic and Health Surveys to estimate multilevel hazard models that identify associations between infant mortality and region-level prevalence of polygyny for 236,336 children in 260 subnational regions across 29 sub-Saharan African countries. We find little evidence that the prevalence of polygyny influences mortality for infants in nonpolygynous households net of region-level socioeconomic factors and gender inequality. However, the prevalence of polygyny significantly amplifies the survival disadvantage for infants in polygynous families. Our findings demonstrate that considering the broader marital context reveals important insights into the relationship between family structure and child well-being.     

New evidence about effects of reproductive variables on child mortality in sub-Saharan Africa

There is still considerable uncertainty about how reproductive factors affect child mortality. This study, based on Demographic and Health Survey data from 28 countries in sub-Saharan Africa, shows that mortality is highest for firstborn children with very young mothers. Other children with young mothers, or of high birth order, also experience high mortality. Net of maternal age and birth order, a short preceding birth interval is associated with above average mortality. These patterns change, however, if time-invariant unobserved mother-level characteristics of importance for both mortality and fertility are controlled for in a multilevel–multiprocess model. Most importantly, there are smaller advantages associated with longer birth intervals and being older at first birth. The implications of alternative reproductive ‘strategies’ are discussed, taking into account that if the mother is older at birth, the child will also be born in a later calendar year, when mortality may be lower.     

Land use as a mediating factor of fertility in the Amazon

Despite implications for both humans and the environment, a scant body of research examines fertility in forest frontiers. This study examines the fertility–environment association using empirical data from Ecuadorian Amazon between 1980 and 1999. Fertility dramatically declined during this period, and our empirical models suggest that households’ relationship to land partially explains this decline. Controlling for known fertility determinants such as age and education, women in households lacking land titles experienced a 27 % higher birth rate than did women in households with land titles. This suggests insecure land tenure was associated with higher fertility. Furthermore, each additional hectare of new pasture was associated with a 16 % higher birth rate, suggesting the potential role of a more stable and lucrative income source in supporting additional births. Findings from this research can help inform strategic policies to address sustainable development in frontier environments.     

Nutrition and Fertility in Bangladesh: Breastfeeding and Post Partum Amenorrhoea

From 1975 to 1980 a prospective study a nearly 2,500 married, fertile women was conducted in Matlab, Bangladesh at the International Centre for Diarrhoeal Disease Research. Women were interviewed at monthly intervals to collect information on nutritional and reproductive status, in order to study the factors associated with natural fertility. The median duration of amenorrhoea for women with no child deaths was 15.5 months, with older women and those of higher parities recording longer durations than younger women or those of lower parities. Median duration of amenorrhoea for women with six or more years of education was 8.4 months compared to 16.4 months among women with no education. When classified by weight at pregnancy termination, average duration of amenorrhoea of women weighing less than 38 kg was 17.6 months compared to 13.6 months among women weighing more than 44 kg. Proportional hazards analyses show that mother's education, parity, month of birth, supplementation practices and nutritional status were significantly associated with the probability of resuming menstruation.     

A marriage trichotomy and its applications

This paper promotes research methods specific to men, the new focus of fertility and family planning studies (especially in sub-Saharan Africa). I propose a novel marriage categorization based on married men’s intentions to take another wife. The three marriage groups are currently monogamous men who intend to remain so, currently monogamous men who intend to become polygynous, and currently polygynous men. The first analysis demonstrates that typical marriage analyses may misclassify men who intend to become polygynous. Applications of the marriage trichotomy illustrate that men with varying marital intentions have differing desires regarding fertility and family planning.     

Family limitation among the Old Order Amish

Summary This paper shows that the Indiana Amish, a high-fertility Anabaptist population, regulate their marital fertility according to their family finances. We linked demographic data from the Indiana Amish Directory with personal property tax records at 5, 15 and 25 years after marriage and found fertility differences by occupation and wealth. Correlations between family size and wealth at the beginning, middle and end of childbearing years were positive. Wealthier women exhibited higher marital fertility, had longer first birth intervals, were older at the birth of their last child, and had larger families than poorer women. Over the past 30 years, marital fertility has remained constant among older women; but birth rates among younger women have been rising rapidly.     

Polygyny and reproductive behavior in sub-saharan Africa: A contextual analysis

In this paper I examine the effect of polygyny on aggregate reproductive behavior. I argue that within countries there exist different polygyny regimes, each exhibiting a unique reproductive pattern. Using the 1988/1989 Kenya Demographic and Health Survey (KDHS1) data, I identify three distinct regimes: low-polygyny, mid polygyny, and high-polygyny regimes. The results of the bivariate and multivariate analyses reveal strong differences in reproductive preferences and behaviors across polygyny regimes. High-polygyny regimes, for instance, maintain a value orientation that favors and encourages high reproductive performance. The force of this pronatalism operates equally for men and women; but whereas men in this regime attain their reproductive goals by marrying multiple wives, women attain theirs by maximizing their reproductive capabilities. This maximization occurs through early initiation of sexual/reproductive activity, universal marriage and minimal interruption of marriage, nonuse of contraception within a union, and a positive attitude toward high fertility.     

Findings and implications of a correlation analysis of the closed and the open birth intervals

A correlation analysis of data on four fertility variables viz. closed birth interval, open birth interval, age and parity, collected in a survey of about 2,000 married women in the reproductive ages in rural India, is carried out in order to study the interrelationships among these variables. Two hypotheses are formulated governing the relationship of the closed and open birth intervals with the fecundability distribution of fertile women, and Parity Progression Ratios which are largely influenced by the proportion of women becoming sterile after each parity. The data lend support to the hypothesis that while the closed intervals are influenced mainly by the distribution of fecundability of women of non-zero fecundability, the open birth intervals are influenced mainly by Parity Progression Ratios or the proportion of women becoming secondarily sterile after each parity. The analysis suggests that we can use the mean open intervals of women classified by parity as indices of fertility, and such an index is comparable to the index of average age of women of given parity. In areas where it is difficult to ascertain the correct age of women this might be of practical value.     

子女孩次性别结构与女性再生育——基于孩次性别递进生育率的分析

现有子女的孩次性别结构是影响女性再生育的重要因素。使用中国2000年人口普查数据和时期孩次性别递进生育指标对女性生育水平进行了测算。结果显示,女性普遍生育但终身只生育一个孩子的比例很大,基于孩次性别结构的生育行为体现了男孩偏好;城市和镇在生育第一孩时就存在性别选择;第一个孩子是女孩的女性生育二孩的可能性较大,且二孩是男孩的比例显著大于是女孩的比例;第一个孩子是男孩的城市和镇的女性大部分不再生育,而农村女性有很大比例会生育二孩,但几乎不存在性别选择。采用某地区2019年的数据进行补充验证,同样发现:只有一个女孩的女性相比较只有一个男孩的女性生育者生第二孩的可能性要高很多,以上研究发现对当前二孩生育行为具有一定的启示意义。     

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.     

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)     

On Postponement and Birth Intervals

Much of the literature on fertility transition presumes that birth control is practiced either to limit family size or to space births. This article argues that women also use birth control to postpone pregnancy. Postponement is not synonymous with spacing. It arises when women delay their next birth for indefinite periods for reasons unrelated to the age of their youngest child, but without deciding not to have any more children. Postponement has a distinctive impact on the shape of birth‐interval distributions that differs from the impacts of family size limitation, birth spacing, or a mixture of the two behaviors. Some populations, such as that in South Africa, have developed fertility regimes characterized by birth intervals far longer than can be accounted for by birth spacing. Postponement of further childbearing that eventually becomes permanent may be an important driver of the transition to lower fertility in sub‐Saharan Africa.