Season of birth has been shown to correlate with many aspects of somatic and mental disorders, development and social adaptation (so-called ‘birth-date effects’). In a sample of young Swedish men, corresponding roughly to a one-year birth cohort, the results of intelligence tests, psychologists’ ratings of psychological function, school achievement, body height, weight and self-reported health during childhood, were found to be correlated with month of birth, and – more strongly – father’s socioeconomic status. The results were more favourable for men who were born during March–May (the period of highest birth rate), and whose fathers were of higher socioeconomic status, than for those born in November and December (the period of lowest birth rate), and whose fathers were in the lower socioeconomic group. It seems reasonable to conclude, from this study and previously reported findings, that these so-called ‘birth-date effects’ are determined by varying and often interacting biological and psychosocial factors. Among these factors, the light-induced entrainment of circadian and annual rhythms in the fetus and/or infant seems to be of pivotal importance. The organization of children into one-year age classes therefore produces an unfair lack of equality of possibilities.

This study investigates the possible effects of pre-term births and low birth weight on infant mortality rates (IMRs) over a 15-year period in Ribeirão Preto, Brazil, based on surveys carried out in 1978/79 and 1994. The 1978/79 survey included 6750 births over a 12-month period and the 1994 survey 2846 births over a 4-month period. Infant deaths were retrieved monthly from the city register. Infant mortality rate decreased from 36·6 to 16·9 deaths per 1000 over 15 years. The decrease in IMR was larger in the 2500–2999 g group than in any other group. The observed falls in IMR were attributable to decreases in birth-weight-specific mortality rates. Likewise, there was a general decrease in IMR in mild, moderate and severe pre-term births. The incidence rate ratio of infant mortality between surveys was 0·46 (95% CI 0·34–0·63); it increased to 0·57 (95% CI 0·35–0·75) when adjusted for birth weight and other factors in the model and rose to 0·69 (95% CI 0·49–0·97) when adjusted for length of gestation and other variables. The increase in pre-term births and low birth weight may have had, at most, a marginal effect on the IMR. Progress in the care of newborns may have decreased the mortality risk, but even mild pre-term birth still has an impact on infant mortality. There is room for further improvement in IMR by tackling the high rates of pre-term birth.

The pill is the most popular family planning method in Bangladesh. However, the failure rate of this method in Matlab, a typical rural area, has been found to be very high. It is estimated that with the current level of failure of the pill and other temporary contraceptives in Matlab, it is unlikely that fertility in Bangladesh will come down to replacement level without a change in contraceptive method mix. It is, therefore, important to know the reasons for the high failure in pill use. Data for this study came from a case-control study in Matlab. A pill failure was considered a case, and no-failure was considered a control. The study included 167 cases and 167 controls. In addition, five focus group discussions were conducted to supplement the data collected from the cases and controls to gain a deeper understanding of pill failure. Results of the analysis of both quantitative and qualitative data suggested that the following were the risk factors for pill failure: no mobility of women, poor knowledge of women about the effectiveness and consequences of drop-out from pill use, weak confidence in the pill, a gap between the use of subsequence pill cycles, delay in starting the pill after menstruation for the first use, not taking any measures consistently for missing the pill, and not following the arrow sign given on the pill cycle. Extensive training of field workers and pill users, covering the reasons for pill failure identified in this study and strong supervision of the work of field workers, is likely to reduce the rate of pill failure in Bangladesh. Also, information, education and communication services for users, and management of side-effects, may be helpful in reducing pill failure.

Fertility levels have dropped substantially in Latin America in recent decades, fuelled by increased contraceptive use and notably a method mix skewed towards female sterilization. This study examined choice of female sterilization in four Latin American countries: Brazil, Colombia, the Dominican Republic and Peru. Data were drawn from national Demographic and Health Surveys conducted in 1995–1996. Discrete-time hazard models were used on the five-year calendar modules of women’s reproductive histories to consider the effects of a number of sociodemographic and contextual determinants as they pertained to status at the moment of the event. The results revealed that the likelihood of a woman’s having undergone contraceptive sterilization was increasing over time in Brazil and Peru, suggesting that the potential for future growth of this method remains strong. A consistent pattern of increased probability of sterilization with higher education was seen across all countries, seemingly dispelling certain controversial claims that the procedure may have been disproportionately performed on the poor. At the same time, the multilevel analytical approach pointed to significant cluster-level random effects, suggesting that there were additional unmeasured contextual influences on women’s propensity to choose sterilization.

It has been established that the probability that a man is homosexual is positively related to his number of older brothers, but not older sisters when the brothers are accounted for. This is known as the ‘fraternal birth order’ effect. In the past, efforts have been made to explain this phenomenon in terms of several alternative biological hypotheses and a psychosocial hypothesis. This note examines how well these hypotheses accommodate the fraternal birth order effect. It is concluded that: (1) the evidence for the hypothesis of maternal immunoreactivity to the male fetus is weak; (2) the evidence for the intrauterine hormone exposure hypothesis is also weak; (3) the evidence for the hypothesis of postnatal learning is stronger. Lastly, there seem likely to be causes common to male homosexuality and paedophilia. They may include sexual (or quasi-sexual) experience in childhood or adolescence.

This paper focuses on the clinical and social diagnostics of stroke-like symptoms in Limpopo Province, South Africa. The research questions addressed here are: what are the lay understandings of strokelike symptoms and what are the health-seeking behaviours of Tsongan Mozambican refugees and South Africans in this area? The study site is ten villages in the Agincourt sub-district of Limpopo Province which are within the health surveillance area of the Agincourt Health and Population Unit (AHPU) of the University of Witwatersrand. The population are Tsongan who speak Shangaan and comprise self-settled Mozambican refugees who fled to this area during the 1980s across the nearby border and displaced South African citizens. The latter were forcibly displaced from their villages to make way for game reserves or agricultural development and moved to this area when it was the former ‘homeland’ of Gazankulu. The team collected data using rapid ethnographic assessment and household interviews as part of the Southern Africa Stroke Prevention Initiative (SASPI). The main findings are that stroke-like symptoms are considered to be both a physical and social condition, and in consequence plural healing using clinical and social diagnostics is sought to address both these dimensions. People with stroke-like symptoms maintain their physical, mental and social well-being and deal with this affliction and misfortune by visiting doctors, healers, prophets and churches.

This study investigated the social factors associated with body-shape preferences for females and males as perceived by Arab women living in Qatar, and correlated the current weight status of women studied with these preferences. The subjects were 535 non-pregnant Arab women aged 20–67 years, who attended heath centres in Doha City, the capital of the State of Qatar. Illustrations of male and female body shapes ranging from very thin to very obese using the 9-figure Silhouettes scale were shown to women, and they were asked to select their preferred figure. Body mass index (BMI) was used to determine the weight status of women studied. Age, educational level and employment status were found to be significantly associated with ideal body-shape preference for both males and females, whereas marital status and current weight status had no significant association. In general, the Arab women studied selected a more mid-range of body fatness for males than for females. It is concluded that attention should be given to sociocultural factors, such as body-shape preferences, in any programmes to promote ideal body weight for the public.

The aim of this study is to test prevailing assumptions that Guatemalan men are authoritative or aloof husbands and, in turn, are either problematic or irrelevant to child health. Based on survey data collected in 1994–95 about 959 children, this research examines whether, how and why husbands were involved in recent episodes of young children’s illness and sheds light on the potential effect of husband involvement on treatment. A relatively high percentage of women reported that they asked for advice or assistance from their husbands regarding child illness, and, contrary to popular notions, the multivariate analyses suggest that husbands' involvement was not driven by their household authority. Rather, key determinants of whether husbands gave advice or assistance included characteristics of the illness and child and the availability of sources of social support, while key determinants of what kind of support husbands gave (namely whether they gave/bought medicines, recommended a provider visit, or gave other advice or assistance) largely related to characteristics of the illness and child, as well as the availability of biomedical health care providers in the community and ethnicity.

The compact spot-check method was applied to elucidate the daily time and space use patterns of 121 adults from a Bangladeshi village in which the authors had previously found more skin manifestations due to arsenic poisoning in males than females. The analysis of 2178 spot-check data, which were obtained over a net period of 2 days, highlighted that farming and cash-earning activities were almost exclusively conducted by males. This is probably due to the Muslim Bangladeshi norm for females to be ‘sedentary’ in or around their own dwellings. Discussion focuses on the advantages of the compact spot-check method and the possibility that males’ larger energy expenditure and longer exposure to sunlight are responsible for their severer skin manifestations.

The proximate causes of the contraceptive effect of lactation are still a matter of productive debate. This study sought to disentangle the relative impact that intense breast-feeding practices and maternal nutrition have on the regulation of ovarian function in nursing women. A mixed-longitudinal, direct-observational, prospective study was conducted of the return to postpartum fecundity in 113 breast-feeding, well-nourished Toba women. A sub-sample of 70 women provided data on nursing behaviour, daily activities, diet quality and urinary levels of oestrone and progesterone metabolites. Well-nourished, intensively breast-feeding Toba women experienced a relatively short period of lactational amenorrhoea (10·2±4·3 months) and a high lifetime fertility (TFR=6·7 live births/woman). Duration of lactational amenorrhoea was not correlated with any of the nursing parameters under study or with static measures of maternal nutritional status. The results indicated that the pattern of resumption of postpartum fertility could be explained, at least partly, by differences in individual metabolic budgets. Toba women resumed postpartum ovulation after a period of sustained positive energy balance. As the relative metabolic load hypothesis suggests, the variable effect of lactation on postpartum fertility may not depend on the intensity of nursing per se but rather on the energetic stress that lactation represents for the individual mother.

It is hypothesized that recent trends in US and worldwide obesity are, in part, related to an increase in the marginal rate of time preference, where time preference refers to the rate at which people are willing to trade current benefit for future benefit. The higher the rate of time preference, the larger is the factor by which individuals discount the future health risks associated with current consumption. Data from the United States, as well as international evidence, suggest that a relationship between these two variables is plausible. The authors encourage researchers to explore the possible link between obesity and time preference, as important insights are likely to result.

The effects of war-induced anxiety and mental distress on individuals and groups can either be mitigated or exacerbated by ‘humanitarian action’. This paper focuses on two key factors that protect the mental well-being of war-affected populations: organized displacement or assisted relocation; and coordinated humanitarian aid operations that are responsive to local needs. Qualitative data from two internally displaced person (IDP) camps in Eritrea are presented. Analysis of these data serves to substantiate and refine a working hypothesis: that social support of the right type, provided at the right time and level, can mitigate the worst effects of war and displacement on victims/survivors. An integrated model of psychosocial transition is suggested. The implications of this approach for humanitarian policy and practice are discussed in the wider context of current debates and lamentations of the ‘humanitarian idea’.

The relation between individual trait differences, social mobility and social structure is central to social biology. Because genetic variance underlies phenotypic variance in some of these traits, for example IQ, several mechanisms determine the population variance. Polygenic inheritance is the basic mechanism. Social mobility and assortative partner choice distribute the trait variance within generations. This feedback circle is constrained by sociological conditions at several levels of analysis. Fundamental to this theory of social assortment is the relation between social–biological traits and social class on the one hand, and these traits and social mobility on the other hand. The focus here is on the relation between social class, social mobility and cognitive ability. The National Child Development Study is drawn upon, including the last follow-up (1999–2000). By approaching this relationship through various methods, both social–biological and sociological aspects of this research question can be assessed.

The objectives of this article are, first, to provide improved estimates of recent fertility levels and trends in Nepal and, second, to analyse the components of fertility change. The analysis is based on data from Nepal’s 1996 and 2001 Demographic and Health Surveys. Total fertility rates (TFR) are derived by the own-children method. They incorporate additional adjustments to compensate for displacement of births, and they are compared with estimates derived by the birth-history method. Fertility is estimated not only for the whole country but also by urban/rural residence and by woman’s education. The own-children estimates for the whole country indicate that the TFR declined from 4·96 to 4·69 births per woman between the 3-year period preceding the 1996 survey and the 3-year period preceding the 2001 survey. About three-quarters of the decline stems from reductions in age-specific marital fertility rates and about one-quarter from changes in age-specific proportions currently married. Further decomposition of the decline in marital fertility, as measured by births per currently married woman during the 5-year period before each survey, indicates that almost half of the decline in marital fertility is accounted for by changes in population composition by ecological region, development region, urban/rural residence, education, age at first cohabitation with husband, time elapsed since first cohabitation, number of living children at the start of the 5-year period and media exposure. With these variables controlled, another one-third of the decline is accounted for by increase in the proportion sterilized at the start of the 5-year period before each survey.

I have recently written: ‘there seem likely to be causes common to male homosexuality and paedophilia. They may include sexual (or quasi-sexual) experience in childhood or adolescence’ (James, 2004). These words are rather vague and I wish to clarify them here.

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.

The effects of religion, population sub-division and geography on the prevalence of deaf-mutism were investigated using information collected in the 1921 Census of Punjab. The total sample size was 9·36 million, and comprised data on thirteen Hindu castes, seventeen Muslim biraderis and two Sikh castes. A two-way analysis of variance comparing males in Hindu castes in which consanguineous marriage was prohibited, with males in Muslim biraderis which favoured first cousin marriage, indicated major differences with respect to the patterns of deaf-mutism within each religion. In the Muslim population 9·1% of the relative variation in the prevalence of deaf-mutism was inter-biraderi, 36·8% between geographical regions, and 48·8% an interaction between biraderi and region, whereas among Hindus 46·8% of the observed variation was inter-caste, 12·8% inter-region and 33·6% due to caste–region interaction. From a wider disease perspective the results obtained with the Hindu community indicate the significant genetic differentiation associated with caste endogamy. As the overwhelming majority of Hindu marriages continue to be within-caste, it can be predicted that similar levels of inter-caste differences in disease frequency currently exist. By comparison, the lower level of inter-biraderi variation among Muslims is probably indicative of the dissolution of pre-existing caste boundaries and the resultant gene pool mixing that followed the large-scale conversion of Hindus to Islam during Muslim rule in North India from the 13th to the 19th centuries.

A study on perceptions, attitudes and treatment-seeking practices related to schistosomiasis was conducted among the Wasukuma in the rural Magu district of Tanzania at the shore of Lake Victoria where Schistosoma haematobium and mansoni infections are endemic. The study applied in-depth interviews, focus group discussions and a questionnaire survey among adults and primary school children. The perceived symptoms and causes were incongruous with the biomedical perspective and a number of respondents found schistosomiasis to be a shameful disease. Lack of diagnostic and curative services at the government health care facilities was common, but there was a willingness from the biomedical health care services to collaborate with the traditional healers. Recommendations to the District Health Management Team were: that collaboration between biomedical and traditional health care providers should be strengthened and that the government facilities’ diagnostic and curative capacity with regard to schistosomiasis should be upgraded. Culturally compatible health education programmes should be developed in collaboration with the local community.

Few studies have examined the impact of unintended pregnancy on women in developing countries. This paper examines the impact of unintended pregnancy on Indonesian women’s psychological well-being. It is hypothesized that experiencing unintended pregnancy is associated with lower psychological well-being and that use of family planning and small family size are associated with higher levels of psychological well-being. Data are drawn from a 1996 survey of 796 women aged 15–49 from two Indonesian provinces, Lampung and South Sumatra. This article focuses on the 71% of women (n=562) who answered all 41 survey items related to psychological well-being. In cluster analysis, women grouped into three clusters, differentiated by their scores on four scales of well-being established through factor analysis (general negative feelings, satisfaction with relationships, satisfaction with economic/family/personal conditions, and negative feelings regarding domestic issues). Women in cluster 3 were characterized mainly by their high level of psychological well-being. Women in cluster 1 had the lowest level of well-being, and women in cluster 2 were in the middle. Multinomial logistic regression was used to assess jointly the effect of unintended pregnancy, contraceptive use, number of children and other factors on a woman’s level of psychological well-being. Unintended pregnancy was associated with lower levels of psychological well-being and contraceptive use was associated with higher levels of psychological well-being, while number of children was not associated with level of well-being. Women who had experienced an unintended pregnancy were less likely to be in the high psychosocial well-being cluster versus both the medium and low clusters. In addition, women using contraception were more likely to be classified in the high than in the low or medium well-being clusters.

The Standard Progressive Matrices test was standardized in Estonia on a representative sample of 4874 schoolchildren aged from 7 to 19 years. When the IQ of Estonian children was expressed in relation to British and Icelandic norms, both demonstrated a similar sigmoid relationship. The youngest Estonian group scored higher than the British and Icelandic norms: after first grade, the score fell below 100 and remained lower until age 12, and after that age it increased above the mean level of these two comparison countries. The difference between the junior school children and the secondary school children may be due to schooling, sampling error or different trajectories of intellectual maturation in different populations. Systematic differences in the growth pattern suggest that the development of intellectual capacities proceeds at different rates and the maturation process can take longer in some populations than in others.