The study examines the impact of body build on differential fertility patterns in 93 !Kung San and 85 Kavango females from northern Namibia. In both groups shorter females had more offspring, but also more dead offspring, than taller females. The interaction between body weight and fertility was different in both groups and may be due to different nursing behaviour. There was a positive relationship between the typical pedomorphy and fertility in the! Kung San, and directional selection processes may be important.

Adolescents are the focus of many interventions that aim to prevent HIV transmission. In order for these interventions to be effective, it is essential to understand adolescents' sexual behaviour. Using data collected in Yaoundé, Cameroon, in 1997, the study analysed risk exposure and HIV prevalence among 426 men and 510 women aged 15–24. Although risky behaviours seem to be more prevalent among young men, their HIV prevalence remains under 1%. In contrast, HIV prevalence is high among young women (7·5%), even those who report having had few sexual partners. Mixing patterns among sexual partners, and especially the age difference between men and women, do not seem to be sufficient to explain the large male–female discrepancy in HIV prevalence that is evident in these data. The results are therefore probably due to a greater susceptibility to infection of young women than men. This study highlights the necessity of reinforcing prevention campaigns among youth and fighting the obstacles that continue to impede the use of condoms in this population.

This study examines the independent effects of neighbourhood context (i.e. neighbourhood poverty) and exposure to perceived discrimination in shaping risk of obesity over time. Weighted three-level hierarchical linear regression models for a continuous outcome were used to assess the independent effects of neighbourhood poverty and perceived discrimination on obesity over time in a sample of 157 non-Hispanic Black, non-Hispanic White and Hispanic adults in Detroit, USA, in 2002/2003 and 2007/2008. Independent associations were found between neighbourhood poverty and perceived discrimination with central adiposity over time. Residents of neighbourhoods with high concentrations of poverty were more likely to show increases in central adiposity compared with those in neighbourhoods with lower concentrations of poverty. In models adjusted for BMI, neighbourhood poverty at baseline was associated with a greater change in central adiposity among participants who lived in neighbourhoods in the second (B=3.79, p=0.025) and third (B=3.73, p=0.024) poverty quartiles, compared with those in the lowest poverty neighbourhoods. The results from models that included both neighbourhood poverty and perceived discrimination showed that both were associated with increased risk of increased central adiposity over time. Residents of neighbourhoods in the second (B=9.58, p<0.001), third (B=8.25, p=0.004) and fourth (B=7.66, p=0.030) quartiles of poverty were more likely to show greater increases in central adiposity over time, compared with those in the lowest poverty quartile, with mean discrimination at baseline independently and positively associated with increases in central adiposity over time (B=2.36, p=0.020). The results suggest that neighbourhood poverty and perceived discrimination are independently associated with a heightened risk of increase in central adiposity over time. Efforts to address persistent disparities in central adiposity in the USA should include strategies to reduce high concentrations of neighbourhood poverty as well as discrimination.

Twenty-eight South African Negro albinos have been tested for intellectual maturity and body image boundary, characteristics and a comparison made with carefully matched normally pigmented controls. The albinos were found to be more intellectually mature than the controls but the control group showed slightly more diffuse body image boundary differentiation than the albino group.

Biological fertility is poorly measured by the number of children born in industrially advanced societies. The time elapsing from when a couple decides to have a child to clinically recognizable pregnancy is a useful alternative. Time to pregnancy can be collected in broad categories in large samples. A model for condensing important information from such data is presented, which fits several large samples of reported waiting times. It is shown that multiparous women conceive more quickly than primiparous women.

This study examined the potential of the theoretical model proposed by Warren Miller (the Traits/Motives–Desires–Intentions–Behaviour or TDIB model) for investigating the involuntary–voluntary childlessness continuum. The first three stages of the theoretical motivational sequence (motives to desires to intentions) were examined using a purposive sample of 314 childless Polish men and women aged 30–39 (at the time of data collection in September 2013). In Poland, this is the age range when the final decision for or against parenthood is taken. To model the motivational sequence, the Structural Equation Modelling (SEM) technique was applied. The results confirmed the hypothesized relations between the constructs for childless individuals in the analysed age group. Their childbearing desires were found to be good predictors of reproductive intentions, while negative and positive childbearing motives (independently) underpinned their desires. Moreover, positive motives appeared to have a stronger effect on desires than negative ones. The study also documented the psychometric properties of the Polish adaptation of the Childbearing Questionnaire, which was originally developed by Miller to measure childbearing motives. The advantages of using this tool for investigating the involuntary–voluntary childlessness continuum are discussed. Overall, the study validated the theoretical model as well as the adaptation of the Childbearing Questionnaire in the new research context: in the new cultural setting and for examining reproductive choices of a specific subpopulation. Directions for future research that could build on the TDIB model and allow for a deeper understanding of permanent childlessness are outlined.

Using Australian records of human births for the first six decades of the twentieth century, the proportions of male and female births are studied in relation to the mother's age, the father's age, the parents' ages in combination, and certain other factors. The principal data used relate to the years 1931–55, during which over 3 million children were born, yet even so the significant features are not easy to discern.

Masculinity tends to fall as the age of either parent increases. But it is only average or below if one parent is old while the other is young. For high masculinity, both parents must be young.

The Australian data are available in a form which enables the sex ratio to be studied also in relation to (a) the season of the year; (b) urban and rural areas; (c) the different states of the Commonwealth; (d) births inside and outside marriage; and (e) single and multiple births. When the influence of the parents' ages is eliminated, however, it does not appear as though the sex ratio varies significantly with any of these factors.

Genetic structure of the Cumbrian population is examined from data on gene and genotype frequency distributions, on geographical location, and on population movement in two generations.

The population is genetically heterogeneous; the central Lake District particularly, and also Carlisle and the southern periphery, stand out as distinct from the remainder and from each other. Regional subdivision of the population is sufficient to lead to some increased overall homozygosity, but its effect on inbreeding is considerably lower than the inbreeding level within regions, the latter being highest in the Lake District and the southern periphery. Examination of isolation by distance shows distance to be an important determinant of genetic differentiation in Cumbria; local and regional kinship levels are similar to those in alpine Swiss areas. Migration analysis suggests the distinctness of the west coast and southern periphery, and a slight increase in kinship between regions in the last generation.

The measures of genetic distance are closely correlated with each other. The measures of kinship derived from migration frequencies between regions are highly correlated with each other, and with geographical distance, but not with genetic distance. Present migration patterns are insufficient to account for the affinities within and between regions indicated by the genetic variation. It is possible that retention of Norwegian influence over a great length of time in the central Lake District is a major contributory element in present-day genetic heterogeneity in Cumbria.

Although the general objective of this study is to examine the extent to which spouses’ socioeconomic characteristics determine whether modern contraception is used and whether family limitation (the demand for no more children) is desired, its central goal is to evaluate the degree to which the net effect of a woman’s education on those fertility decisions is altered once a control is made for the level of schooling of the husband. Individual characteristics of spouses included as controls in this analysis are on the one hand women’s attributes relating to employment, age, parity, ethnic identity, and urban residence and, on the other hand, the occupation of the husband. Data used in this research are provided by DHS surveys conducted in fourteen sub-Saharan countries: Mali, Burkina Faso, Niger, Nigeria, Cameroon, Benin, Senegal, Ghana, Central African Republic, Kenya, Zambia, Zimbabwe, Namibia and Rwanda. With two dichotomous outcome variables, logistic regression was used to estimate two nested models for each dependent variable and for each country covered by the study. DHS respondents used as units of analysis in this study are women who were married (any kind of union) and non-pregnant at the time when each national survey was conducted. The findings suggest that, while an educated wife needs the support of an educated husband to state a preference for family limitation in contemporary sub-Saharan Africa, controlling for husband’s education and other relevant covariates does little to undermine the evidence that woman’s advanced education and the adoption of modern family planning are positively related in the developing world.

This paper uses prospective data from the Matlab surveillance system in rural Bangladesh to demonstrate that initially co-resident spouses and sons have a major impact on the subsequent mortality of old people, with significant differences by the sex of the elderly person, and the age of the son. Spouses significantly reduce mortality by similar magnitudes for both elderly men and women. On the other hand, co-resident adult sons reduce mortality for elderly women much more than for elderly men, with younger sons being more beneficial than older sons. Furthermore, both married and unmarried females appear to benefit equally from co-resident adult sons. Finally, this analysis suggests that the impact of spouses and sons on mortality in old age is not substantially mediated through changes in elderly economic status.

In recent years there have been attempts to explain religiousness from an evolutionary viewpoint. However, empirical data on this topic are still lacking. In the present study, the behavioural ecological theoretical framework was used to explore the relations between religiousness, harsh environment, fitness (reproductive success and parental investment) and fitness-related outcomes (age at first birth, desired number of children and the romantic relationship duration). The data were collected from 461 individuals from a community sample who were near the end of their reproductive phase (54% females, Mage = 51.75; SD = 6.56). Positive links between religiousness, harsh environment, fitness and fitness-related outcomes were expected, with the exception of age at first birth, for which a negative association was hypothesized. Hence, the main assumption of the study was that religiousness has some attributes of fast life-history phenotypes – that it emerges from a harsh environment and enables earlier reproduction. The study findings partially confirmed these hypotheses. Religiousness was positively related to environmental harshness but only on a zero-order level. Religious individuals had higher reproductive success (this association was especially pronounced in males) but religiousness did not show associations with parental investment. Religiousness was positively associated with desired number of children and negatively associated with age at first birth, although the latter association was only marginally significant in the multivariate analyses. Finally, path analysis showed that desired number of children and age at first birth completely mediated the relation between religiousness and reproductive success. The data confirmed the biologically adaptive function of religiousness in contemporary populations and found the mediating processes that facilitate fitness in religious individuals. Furthermore, the findings initiate a more complex view of religiousness in a life-history context which could be fruitful for future research: a proposal labelled as ‘ontogeny-dependent life-history theory of religiousness’.

It is still unclear if and how biological factors contribute to excess male mortality due to ‘external causes’ (accidents, injuries, homicides and suicides). Sex hormones and reproductive roles are supposed to drive sex differences in behaviours increasing the male external cause mortality risk. This study analyses the external cause mortality of Catholic nuns and monks from three Bavarian cloisters whose similar environments allow the impact of biological factors to be isolated from a number of confounding causes. Using obituaries, entries in the profession books of religious orders and cemetery registers 2533 deaths of nuns and monks could be linked to a specific cause of death for the years 1946–2005, of which 69 belong to the group of external cause deaths. External cause mortality of the Bavarian cloistered and the West German general population has been compared by means of standardized mortality rates (SMRs) for ages 45 onwards using the European age standard for the age groups 45–64, 65–74 and 75+. Whereas nuns show statistically significantly lower external cause mortality than the general female population, monks' external cause mortality parallels or even exceeds that of general population males. These findings contradict the reproductive role hypothesis and provide some evidence for the sex hormones hypothesis.

Consistent findings about the inverse association of social network level with coronary heart disease mortality and morbidity suggest the importance of investigating biological pathways of association. Differences in plasma fibrinogen level were investigated among middle-aged men with weak and strong structural and functional social network ties. Men with low scores in the adequacy of social participation variable (structural) had higher mean values of plasma fibrinogen than those with high scores. The difference remained after adjustment for age, smoking and cardiovascular health status and after possible modifying factors were taken into account, but did not remain significant after allowing for physical fitness. Men with high scores in overall support (functional) had higher plasma fibrinogen levels compared to the men with low scores. This difference persisted after age and cardiovascular health status were taken into account but was explained by smoking. The data suggest that smoking and cardiorespiratory fitness are important mediating or modifying factors between structural and functional aspects of social network ties and plasma fibrinogen.

This examination of the effect of birth spacing on infant and child mortality in rural Nepal is based on data from the Nepal Fertility Survey 1976 carried out by the Nepal Family Planning and Maternal Child Health Project in collaboration with the World Fertility Survey. The study confirms that the higher risk of infant death to first-born children is mainly due to the higher proportions of younger women having first births, rather than due to their being first order births per se. The effect of maternal age on infant and child mortality is largely associated with birth interval. Previous birth interval, therefore, stands out as the most important factor affecting infant mortality; the next most important factor is the survival of the preceding child.

Studies to evaluate use-effectiveness and cost-effectiveness of natural family planning (NFP) were conducted in Liberia and Zambia. The Liberian programme provided uni-purpose NFP services to 1055 clients mainly in rural areas; the Zambian programme provided NFP services integrated with MCH to 2709 clients predominantly in urban areas. The one-year life table continuation and unplanned pregnancy rates were 78·9 and 4·3 per 100 women-years in Liberia, compared to 71·2 and 8·9 in Zambia. However, high rates of loss to follow-up mandate caution in interpretation of these results, especially in Zambia. More women progressed to autonomous NFP use in Liberia (58%) than in Zambia (35·3%). However, programme costs per couple-year protection were lower in Zambia (US$25·7) than in Liberia (US$47·1). Costs per couple-year protection were higher during learning than autonomy, and declined over time. These studies suggest that NFP programmes can achieve acceptable use-and cost-effectiveness in Africa.

The realization that steroidal contraceptives administered immediately after delivery to lactating women may be excreted into milk, and adversely affect the neonate, is a cause for concern. Most investigations on hormonal contraceptives have dealt with the efficacy of ovulation suppression, and systemic side effects, but little is known about the appearance of steroids or their metabolites in milk. Apart from the immediate side effects on the neonate, unforeseen long-term consequences require special consideration. Until research provides us with more information, women should use breast-feeding and IUDs instead of steroidal contraceptives during the first trimester post-partum.

Heights of couples of arranged marriages in Islamabad, Pakistan, were measured. There is an overall significant correlation, and this correlation is maintained when the data are subdivided according to various classifications, e.g. social class. Some hypotheses are put forward to explain the correlations.

Selected determinants of overall infant mortality in Vietnam were examined using data from the 1988 Vietnam Demographic and Health Survey, and factors underlying neonatal and post-neonatal mortality were also compared. Effects of community development characteristics, including health care, were studied by logistic regression analysis in a subsample of rural children from the 1990 Vietnam Accessibility of Contraceptives Survey.

Infant neonatal and post-neonatal mortality rates showed comparable distributions by birth order, maternal age, pregnancy intervals, mother's education and urban–rural residence. Rates were highest among first order births, births after an interval of less than 12 months, births to illiterate mothers and to those aged under 21 or over 35 years of age. Logistic regression analysis showed that the most significant predictor of infant mortality was residence in a province where overall infant mortality was over 40 per 1000 live births. In the rural subsample, availability of public transport was the most persistent community development predictor of infant mortality. Reasons for the low infant mortality rates in Vietnam compared to countries with similar levels of economic development are discussed.

This study explores the association between type of female circumcision and infertility and fertility in Sudan using the 1989–90 Demographic and Health Survey. It is hypothesized that women with either Pharaonic or Intermediate circumcision would have higher infertility and lower fertility compared with women with Sunna circumcision, and that uncircumcised women would have the lowest infertility and highest fertility of the three groups. This hypothesis, a widely held assumption, proved to be largely incorrect. Though women with Pharaonic or Intermediate circumcision did have a higher prevalence of primary infertility than uncircumcised women, women with Sunna circumcision had even lower rates of primary infertility compared with uncircumcised women. This pattern prevailed in multivariate models controlling for confounding variables, where women with Pharaonic or Intermediate circumcision had significantly higher primary infertility. Moreover, though women with Pharaonic or Intermediate circumcision also had the highest prevalence of secondary infertility, once confounding covariates were controlled in multivariate models, there was no significant difference among the three groups of women. With respect to fertility, the total fertility rate was 7·6 for women with Pharaonic or Intermediate circumcision, 8·1 for women with Sunna circumcision and 8·3 for uncircumcised women. Differences in fertility were found to be insignificant when covariates were controlled. The multivariate models were estimated using logistic regression. In conclusion, Pharaonic or Intermediate circumcision may be associated with higher primary infertility while there was no evidence suggesting that either secondary infertility or fertility was associated with a woman’s circumcision status.

Studies have documented substantial increases in obesity throughout most of the industrialized world in recent decades. The majority of explanations for these increases have centred around environmental factors such as the increasing availability of high-fat, high-carbohydrate foods and sedentary lifestyles. This study sought to determine if genetic factors might be contributing to the increases in the proportions of North Americans who are obese and overweight. The body mass index (BMI) for a large sample of two generations of United States and Canadian subjects was correlated with family fertility indicators. Small but highly significant positive correlations were found between the BMIs of family members and their reproduction rates, especially in the case of women. For instance, mothers in the sample (most of whom were born in the 1940s and 50s) who were in the normal or below normal range had an average of 4·3 siblings and 3·2 children, compared with 4·8 siblings and 3·5 children for mothers who were overweight or obese. When combined with evidence from twin and adoption studies indicating that genes make substantial contributions to obesity, this study suggests that recent increases in obesity are partially the result of overweight and obese women having more children than is true for average and underweight women. It is speculated that improvements in medical treatments for conditions associated with obesity – particularly diabetes and heart disease – are making it possible for overweight women to live longer and to be more fertile than was true historically.