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 estimates the effect of dysgenic trends in Taiwan by exploring the relationships among intelligence, education and fertility. Based on a representative adult sample, education and intelligence were negatively correlated with the number of children born. These correlations were stronger for females. The decline of genotypic intelligence was estimated as 0.82 to 1.33 IQ points per generation for the Taiwanese population.

A geographically stratified cross-sectional survey was conducted in 2002 to investigate household-level factors associated with use of mosquito control measures and self-reported malaria in Malindi, Kenya. A total of 629 households were surveyed. Logistic regressions were used to analyse the data. Half of all households (51%) reported all occupants using an insecticide-treated bed net and at least one additional mosquito control measure such as insecticides or removal of standing water. Forty-nine per cent reported a history of malaria in the household. Of the thirteen household factors analysed, low (OR=0·23, CI 0·11, 0·48) and medium (OR=0·50, CI 0·29, 0·86) education, mud–wood–coral (OR=0·0·39, CI 0·24, 0·66) and mud block–plaster (OR=0·47, CI 0·25, 0·87) wall types, farming (OR=1·38, CI 1·01, 1·90) and travel to rural areas (OR=0·48, CI 0·26, 0·91) were significantly associated with the use of mosquito control, while controlling for other covariates in the model. History of reported malaria was not associated with the use of mosquito control (OR=1·22, CI 0·79, 1·88). Of the thirteen covariates analysed in the second model, only two household factors were associated with history of malaria: being located in the well-drained stratum (OR=0·49, CI 0·26, 0·96) and being bitten while in the house (OR=1·22, CI 0·19, 0·49). These results suggest that high socioeconomic status is associated with increased household-level mosquito control use, although household-level control may not be enough, as many people are exposed to biting mosquitoes while away from the house and in areas that are more likely to harbour mosquitoes.

In 1996, the Ministry of Health in Ghana included emergency contraception (EC) in its newly issued National Reproductive Health Service Policy and Standards. A short survey was conducted in the summer of 1997 to evaluate health providers' knowledge of EC. Of the 325 providers interviewed, about one-third (34%) had heard of EC. No provider had sufficient knowledge to prescribe EC correctly. A well-coordinated training programme for providers will have to precede successful introduction of EC in Ghana. Moreover, a dedicated product may be critical for the successful introduction of EC in a country like Ghana, where provider knowledge is low.

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.

The Shetland Islands lie in the North Atlantic approximately equi-distant between Scotland, Norway and the Faroes. The earliest known colonizers came from the Mediterranean, but when the Vikings arrived (c. AD 800), there seem to have few or no human inhabitants. The descendants of the west Scandinavians who came to the islands in the early Viking movement still comprise the bulk of the human population, and form a series of isolates unique in the United Kingdom.

The paper summarizes the available information on the origins and physical characteristics of the Shetlanders. Much of this is trivial, but in the absence of any other review we have brought together what is known. The only blood group data are ABO frequencies which are similar to those on the other North Atlantic islands (Orkney, Faroe and Iceland). The best estimates of relationship are based on comparisons of non-metrical skull variant frequencies which show that the nearest relatives of the Shetlanders are the inhabitants of Jaeren in southern Norway. The same conclusion comes from independent evidence of linguistic affinities.

Shetland has the highest known prevalence of multiple sclerosis in the world, and possibly a high incidence of gastric ulceration. It also has a large number of standard Down's syndrome (trisomy-21) patients. These could be the result of the fathers' periodic absences at sea, resulting in their families being spread over a large span of years. Clearly there are interesting and possibly important morbidity and mortality factors operating in the population—which could give significant information about genetical factors in disease. Data on mental defect and psychiatric disease are also presented.

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.

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.

Causality for the seasonality of human births, which affects populations wordwide, has been a profound mystery for nearly two centuries. Most explanations for seasonality fail because of inconsistent global application. In two previous studies, Cummings (2002, 2003) hypothesized that human reproduction has been responsive to changes in both seasonal environmental light intensity (surface luminosity) and photoperiod. Except at higher latitudes, photoperiod is of secondary importance to that of environmental light intensity. Because of a lack of data, the presence or lack of cloud cover is used as a general proxy for environmental light intensity. These studies show a positive correlation between conceptual seasonality and cloud cover on a worldwide basis, and propose that there is a delay between exposure to increased light and the onset of conceptions. This delay is three months at higher latitudes and one to two months for lower latitudes. Both studies suggest that an excellent means of hypothesis confirmation would be to provide one or more examples of how a seasonal change in cloud cover might alter the number of conceptions in subsequent months. The present study tests this hypothesis. The percentage of possible sunshine and averaged sunshine hours are used to investigate their influence on seasonality of births in Germany and the Netherlands. The evidence shows that a seasonal change in environmental light intensity preceded a change in the peak months for conceptions in Germany and the Netherlands. Although secondary influences are possible, the primary reason for this transition in peak conceptual months seems to be related to the seasonal changes in environmental light intensity for both countries. Although this transitional relationship was predicted in Cummings (2002, 2003), further research is required, especially with regard to more precise measurements of environmental light intensity and its physiological effect on the human endocrine system.

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.

The study analysed the HIV/AIDS situation in Zambia six years after the onset of mass campaigns of Voluntary Medical Male Circumcision (VMMC). The analysis was based on data from Demographic and Health Surveys (DHS) conducted in 2001, 2007 and 2013. Results show that HIV prevalence among men aged 15–29 (the target group for VMMC) did not decrease over the period, despite a decline in HIV prevalence among women of the same age group (most of their partners). Correlations between male circumcision and HIV prevalence were positive for a variety of socioeconomic groups (urban residence, province of residence, level of education, ethnicity). In a multivariate analysis, based on the 2013 DHS survey, circumcised men were found to have the same level of infection as uncircumcised men, after controlling for age, sexual behaviour and socioeconomic status. Lastly, circumcised men tended to have somewhat riskier sexual behaviour than uncircumcised men. This study, based on large representative samples of the Zambian population, questions the current strategy of mass circumcision campaigns in southern and eastern Africa.

This study reports an ecologic analysis of the relationship between mean birth weight (MBW) and nutritional, medical and social variables, using 1982 data for 47 prefectures in Japan.

Correlation analysis showed that variables that correlated significantly with MBW were mean temperature (r=0·63), total calorie intake (r=0·56), and body mass index of women (r=0·60). It is concluded that the MBW level in a given community represents the long and short term nutritional condition of mothers, and that the level may follow Bergman’s law: ‘In the same species, the body size of an animal increases along with latitude; that is, the lower the temperature, the larger the body size’.

In Afghanistan, acute respiratory infection (ARI) is a leading cause of under-five mortality. Previous studies on the effects of cooking fuel on ARI have only looked at the types of cooking fuel, and not the effects of the location of the cooking place. The present study aimed to assess the effects of fuel type and place of cooking on the prevalence of ARI among under-five children in Afghanistan. Descriptive statistics and multilevel logistic regression analysis were performed for 31,063 children using data from the first round of the Afghanistan Demographic and Health Survey conducted in 2015. Overall, 13% of the children suffered from ARI symptoms in the 2 weeks before the survey, but this varied widely across the country. The multilevel analysis showed that, compared with households using clean cooking fuel in a separate building or outside, households using clean cooking fuel within the house and without a separate kitchen had a 32% lower risk [95% confidence interval (CI)=0.51–0.91] of having under-five children with ARI, and those using clean fuel in a separate kitchen in the house had a 17% lower risk (95% CI=0.67–1.03). On the other hand, households using polluting cooking fuel in the house without a kitchen had a 14% (95% CI=0.91–1.44) higher risk of having under-five children with ARI, and those using polluting cooking fuel in the house with a separate kitchen had a 5% (95% CI=0.85–1.30) higher risk, after adjusting for other covariates. The findings indicate that type of cooking fuel is not the only issue affecting ARI in children. Place of cooking (in a house with or without a separate kitchen versus outside) also affects the risk of ARI among under-five children. The study also found that mother’s education and occupational status, community poverty and ethnicity are other important factors affecting the prevalence of ARI in under-five children in Afghanistan.

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.

Demographic research in India over the last two decades has focused extensively on fertility change and gender bias at the micro-level, and less has been done at the district level. Using data from the Census of India 1991–2011 and other sources, this paper shows the broad pattern of fertility transition and trends in the child sex ratio in India, and examines the determinants of the child sex ratio at the district level. During 1991–2011, while the Total Fertility Rate (TFR) declined by 1.2 children per woman, the child sex ratio fell by 30 points in the districts of India. However, the reduction in fertility was slower in the high-fertility compared with the low-fertility districts. The gender differential in under-five mortality increased in many districts of India over the study period. The decline in the child sex ratio was higher in the transitional compared with the low-fertility districts. The transitional districts are at higher risk of a low child sex ratio due to an increased gender differential in mortality and increase in the practice of sex-selective abortions. The sex ratio at birth and gender differential in mortality explains one-third of the variation, while region alone explains a quarter of the variation in the child sex ratio in the districts of India.

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.

Synchronous with the decline in fertility that took place in the post-war period in the Netherlands, patterns of birth seasonality changed as well. In this paper seasonal fluctuations in fertility in the Netherlands are examined using population register data for the period 1952 to 2005. The peak in births has changed from spring to summer and subsequently to August/September, thereby shifting from the European to the American pattern. The seasonal shift can be attributed to parity-specific changes. Before the transition, birth seasonality did not differ much between the different parities. In the transition period from higher to low fertility, differences between parities increased which persist up to today. At present, the overall seasonality pattern is determined by first births. Moreover, birth seasonality varies by maternal age. The findings stimulate the discussion on the role of planning as a cause of birth seasonality.

Millions of children who were born during the first decade after the Islamic revolution in Iran are now reaching the age of marriage and childbearing. Short spacing between marriage and the birth of the first child has the potential to cause an excessive and costly increase in the growth of population in Iran. Research into the motivations for the birth of first child among newly married couples can create a knowledge base that will enable health centres to help these couples make better decisions about the timing of their first pregnancy. Using a consecutive sampling technique and administering Miller’s Childbearing Questionnaire, data were gathered regarding the childbearing motivations and desires of 300 couples who had been referred to the Shiraz Health Center for premarital counselling. The Childbearing Questionnaire, with some minor modifications, was found to be a valid and reliable instrument for measuring the childbearing motivations of newly married couples of Shiraz County, Fars Province, Iran. The utility of these findings for counselling in health centres is discussed. Based on the results, a longitudinal study is being designed that will allow the development of models for predicting the time of first pregnancy after marriage.

This paper examines whether low income is a barrier to contraceptive use in Pakistan, a country in which economic conditions are deteriorating at a time when the private sector is becoming a more important supplier of contraception. Multivariate regression analysis performed using the Pakistan Contraceptive Demand Survey suggests that low income is a deterrent to modern contraceptive use in Pakistan. This is particularly the case for contraceptive methods supplied through the private sector. It is concluded that, if the aim of family planning programmes is to reach low-income people, the prices of contraceptives supplied through the private sector should be kept as low as possible.

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’.