A study has been made of twinning rates throughout the world over the last two decades. There has been a decline in age-specific dizygotic twinning rates in almost all of the developed countries during this period. Exceptions to this trend are provided by the United States, where the only decline in twinning rates in the last two decades was in births to older women in the 1960s, and by Czechoslovakia, Hungary and Bulgaria, where an initial decline in twinning during the 1960s was followed by stable twinning rates.

It is suggested that the cause may be some form of environmental pollutant, perhaps a pesticide, which has been the subject of restrictive legislation first in the United States and later in the three Communist countries. Possibly the cause of this decline may be identified by a study of such legislation.

This seems to be the first study of twinning rates in Central and South America. The low twinning rates in some of the countries there may indicate the genetic affiliations of their inhabitants with those (of Mongoloid origin) of countries in the Far East.

The study analyses various sex differences observed among children in WFS and DHS surveys conducted in sub-Saharan Africa. Four outcome indicators are presented: neonatal mortality, postneonatal mortality, child mortality and prevalence of malnutrition. Three indicators of health seeking behaviour are presented: vaccination, oral rehydration therapy and duration of breast-feeding. The statistical analysis focuses on comparison of the observed distributions of the sex ratios to theoretical distributions expected from the sample sizes of the various surveys. The results show the absence of any difference in health seeking behaviour between boys and girls, whether for preventive medicine (vaccination), curative medicine (oral rehydration therapy) or feeding practices (breast-feeding). On the other hand, mortality appears to be consistently higher for boys, more so among neonates (+28%) than among 1–12-month-olds (+8%) and 1–4-year-olds (+4%), and similarly malnutrition appears to be more prevalent among boys (+5%). The contrast between the lack of differences in behavioural indicators and the significant differences in outcome indicators suggests a biological causality. Results are discussed in the light of biological factors.

This study was carried out by the Turkish Republic Ministry of Health to determine the prevalence of consanguineous marriage and its correlates with socio-demographic and obstetric risk factors in women in Turkey. The cross-sectional, national-level study was carried out from October to December 2013. The study population was composed of women between the ages of 15 and 65 years living in Turkey. The sample size was calculated as 9290 houses within Turkey’s 81 provinces so as to improve the Turkish rural–urban expectations by means of systematic stack sampling according to the Turkish Statistical Institute’s address-based vital statistics system. The target sample size was 6364, but only eligible 4913 women, who had been married, were included in the study. The consanguineous marriage frequency in the sample was found to be 18.5%, and of these 57.8% were first cousin marriages. Women living in an extended family and whose education level and first marriage ages were low, and whose perceived economic status was poor, had higher frequencies of consanguineous marriage (p<0.001). Consanguineous marriage frequencies were higher (p<0.001) for women who had spontaneous abortions and stillbirths or who had given birth to infants with a congenital abnormality. In this context, it is important to develop national policies and strategies to prevent consanguineous marriages in Turkey.

While the ‘immigrant health paradox’ posits better health behaviours and outcomes for immigrants upon arrival to the US, research suggests that this advantage may deteriorate over time. This study analysed the relationship of acculturation and breast-feeding initiation and duration among a sample of predominantly Latina, low-income women in the US. The four measures of acculturation included: mother’s nativity (foreign born vs US born), mother’s parents’ nativity (foreign born vs US born), years of US residence (<8 years vs ≥8 years) and a dichotomous measure of language acculturation adapted from three items on Marin’s acculturation scale (preferred language spoken at home, reading language and writing language) as exclusive use of native language versus non-exclusive use (mixed or English only) (Marin et al., 1987; Marin & Gamba, 1996). Final multivariable models showed that mothers who exclusively used their native language were more likely to initiate breast-feeding as well as breast-feed for longer duration compared with mothers with non-exclusive use, whereas years of US residence and mother’s nativity were not significantly associated with breast-feeding initiation or duration. Mother’s parents’ nativity also emerged as a significant predictor of breast-feeding duration, both within final models for immigrants and across study participants. Programmes providing nutrition education to low-income women may wish to consider the role of language as an important determinant of breast-feeding. The role of mother’s parents’ nativity on breast-feeding practices deserves exploration in future studies, as the cultural practices taught by family members born outside the US may exert strong pressure within immigrant families now living in the US.

During the first half of this century, the seasonal pattern of births in European countries showed a major peak in the spring and a minor peak in the autumn. In contrast, the pattern in the US was of a minor peak in spring and a major peak in autumn. Over the last 20 years, the pattern in England and Wales has changed to resemble the US pattern, and the same seems to be true of several other European countries. A hypothesis is offered to account for the difference between the European and the US patterns and for the change from one to the other in some countries.

The magnitude of seasonality correlates positively with latitude: it is suggested that this is partially consequent on variation in luminosity.

This analysis investigates the determinants of contraceptive discontinuation in six developing countries, using data from Phase I surveys of the DHS programme. Cumulative probabilities of discontinuation at 24 months for reasons other than the desire for another child were examined. By this time, typically about 40% of couples have stopped use and most are subsequently at risk of an unwanted conception. Discontinuation of IUD use was found to be less common than for other methods, partly perhaps because cessation of use requires a deliberate decision to have the device removed.

The most important results are negative ones. Neither the schooling of couples nor their type of residence exerted appreciable influence on discontinuation. The policy and programme implications are discussed. Prior use of a method, fertility preferences and the related demographic factors of age and family size emerged as pervasive predictors of discontinuation.

In 1993, the Navrongo Health Research Centre launched a new demographic research system for monitoring the impact of health service interventions in a rural district of northern Ghana. The Navrongo Demographic Surveillance System uses automated software generation procedures that greatly simplify the preparation of complex database management systems. This paper reviews the Navrongo model for data collection, as well as features of the Navrongo system that have led to its replication in other health research projects requiring individual-level longitudinal demographic data. Demographic research results for the first 2 years of system operation are indicative of a pretransitional rural society with high fertility, exceedingly high mortality risks, and pronounced seasonal out-migration.

Understanding care-seeking practices and barriers to prevention of mother-to-child transmission (PMTCT) of HIV is necessary in designing effective programmes to address the high disease burden due to HIV/AIDS in Uganda. This study explored perceptions, care-seeking practices and barriers to PMTCT among young and HIV-positive women. A household survey (10,706 women aged 14–49 years), twelve focus group discussions and 66 key informant interviews were carried out between January and April 2009 in Wakiso district, central Uganda. Results show that access to PMTCT services (family planning, HIV counselling and testing and delivery at health units) was poor. Decision making was an important factor in accessing PMTCT services. Socioeconomic factors (wealth quintile, age, education level) and institutional practices also influenced access to PMTCT. Overall, having had an HIV test was highest when both men and women made decisions together or when women were empowered to make their own decisions. This was significant across wealth quintiles (p=0.0001), age groups (p=0.0001) and education levels (p=0.0001). The least level of HIV testing was when men made decisions for their spouses; and this was the case with family planning and deliveries at health units. Other barriers to PMTCT were fear of women and male spouses to have an HIV test and the perception that HIV testing is compulsory in antenatal clinics. In conclusion, to increase access to PMTCT among women, especially the young, poor and least educated, there is a need to empower them to make decisions on health seeking, and also to empower men to support their spouses to make good decisions. Other barriers like fear of having an HIV test should be addressed through appropriate counselling of clients.

Worldwide, there is increasing recognition that if family and reproductive health programmes are to be successful, the involvement of men is essential. As part of the problem, men also have to be seen as part of the solution. The reality is that in many countries, including Turkey, men generally do not accompany their partners to health facilities for family planning, antenatal and postnatal services and are not expected to attend the labour or birth of their child. Workplace programmes are a potential strategy for meeting the reproductive health education needs of men in industrial cities such as Istanbul. This intervention study was developed to test the feasibility and effects of expanding a special programme for expectant fathers to large workplaces in Istanbul, with the aim of improving the health of Turkish families during the pregnancy, birth and newborn periods. The findings indicate that it is possible to train workplace physicians in Istanbul to conduct regular educational programmes for expectant fathers on reproductive health, and that such programmes may have beneficial effects, especially in the areas of pregnancy nutrition, exclusive breast-feeding, and support behaviours. Considering the difficulty of getting men to attend hospital or clinic-based educational programmes in large urban areas, bringing such training programmes to men at their places of work has the potential to be an important strategy. Given that large workplaces in Turkey already have full-time physicians charged with the duty of health education for employees, this is also a feasible strategy.

Perceived discrimination has been linked to poor health outcomes among ethnic and racial minorities in the United States, though the relationship of discrimination-related stress to immigrant health is not well understood. This article reports findings from a preliminary study that examined blood pressure and Epstein-Barr virus antibody levels in relation to self-reported indicators of stress, acculturation and social support among 79 adult immigrant Latino farm workers in Oregon, US. Findings show that increases in discrimination-related stress predicted elevated systolic blood pressure (SBP) and Epstein-Barr virus antibody levels among male participants. Though female participants reported similar levels of discrimination stress, this perceived stress was not reflected in biological measures. Among women, greater English language engagement was linked to higher SBP, and more years in the US was associated with higher diastolic blood pressure. Study results suggest that male and female immigrants' physiological responses to stress may be influenced in distinctive ways by processes of adjustment to life in the US. If replicated, the finding that discrimination stress predicts elevated SBP may have clinical and public health implications given that elevated SBP is an established risk factor for cardiovascular disease.

The gap in access to maternal health care services is a challenge of an unequal world. In 2015, each day about 830 women died due to complications of pregnancy and childbirth. Almost all of these deaths occurred in low-resource settings, and most could have been prevented. This study quantified the contributions of the socioeconomic determinants of inequality to the utilization of maternal health care services in four countries in diverse geographical and cultural settings: Bangladesh, Ethiopia, Nepal and Zimbabwe. Data from the 2010–11 Demographic and Health Surveys of the four countries were used, and methods developed by Wagstaff and colleagues for decomposing socioeconomic inequalities in health were applied. The results showed that although the Concentration Index (CI) was negative for the selected indicators, meaning maternal health care was poorer among lower socioeconomic status groups, the level of CI varied across the different countries for the same outcome indicator: CI of −0.1147, −0.1146, −0.2859 and −0.0638 for <3 antenatal care visits; CI of −0.1338, −0.0925, −0.1960 and −0.2531 for non-institutional delivery; and CI of −0.1153, −0.0370, −0.1817 and −0.0577 for no postnatal care within 2 days of delivery for Bangladesh, Ethiopia, Nepal and Zimbabwe, respectively. The marginal effects suggested that the strength of the association between the outcome and explanatory factors varied across the different countries. Decomposition estimates revealed that the key contributing factors for socioeconomic inequalities in maternal health care varied across the selected countries. The findings are significant for a global understanding of the various determinants of maternal health care use in high-maternal-mortality settings in different geographical and socio-cultural contexts.

Homosexual men have a higher mean birth order than do heterosexual men, primarily because they have a greater number of older brothers. The purpose of this study was to determine whether the same difference occurs in homosexual vs heterosexual women. The probands were 964 homosexual and heterosexual, male and female volunteers, from whom birth order data were collected with self-administered questionnaires. The homosexual men had more older brothers than the heterosexual men, but they did not have more older sisters, younger brothers, or younger sisters. The homosexual women did not differ from the heterosexual women with regard to any class of sibling. These results are consistent with the hypothesis that the high birth order of homosexual men reflects the progressive immunization of certain mothers to H-Y antigen by succeeding male fetuses, and the increasing effects of H-Y antibodies on sexual differentiation of the brain in succeeding male fetuses.

This study tests two evolutionary hypotheses on grandparental investments differentiated by the child's sex: the paternity uncertainty hypothesis and the Trivers–Willard hypothesis. Data are from two culturally different countries: the Dutch Longitudinal Aging Study Amsterdam (n=2375) and the Chinese Anhui Survey (n=4026). In the Netherlands, grandparental investments are biased towards daughters' children, which is in accordance with the paternity uncertainty hypothesis. But in China, grandparental investments are biased towards sons' children, which is in conflict with the paternity uncertainty hypothesis. This study found no support for the Trivers–Willard hypothesis. These results raise doubts over the relevance of paternity uncertainty as an explanation of a grandparental investment bias towards daughters' children that is often found in Western populations. The results suggest that discriminative grandparental investments are better understood as the outcome of cultural prescriptions and economic motives.

Birth weight is known to be closely related to child health, although as many infants in developing countries are not weighed at birth and thus will not have a recorded birth weight it is difficult to use birth weight when analysing the determinants of child illness. It is common to use a proxy for birth weight instead, namely the mother's perception of the baby's size at birth. Using DHS surveys in Cambodia, Kazakhstan and Malawi the responses to this question were assessed to indicate the relationship between birth weight and mother's perception. The determinants of perception were investigated using multilevel ordinal regression to gauge if they are different for infants with and without a recorded birth weight, and to consider if there are societal or community influences on perception of size. The results indicate that mother's perception is closely linked to birth weight, although there are other influences on the classification of infants into size groups. On average, a girl of the same birth weight as a boy will be classified into a smaller size category. Likewise, infants who died by the time of the survey will be classified as smaller than similarly heavy infants who are still alive. There are significant variations in size perception between sampling districts and clusters, indicating that mothers mainly judge their child for size against a national norm. However, there is also evidence that the size of infants in the community around the newborn also has an effect on the final size perception classification. Overall the results indicate that mother's perception of size is a good proxy for birth weight in large nationally representative surveys, although care should be taken to control for societal influences on perception.

On 26th December 2003, a severe earthquake hit the city of Bam in Kerman province, southern Iran. It destroyed around 90% of houses and at least 60% of the public buildings, and claimed the lives of more than 20,000 persons. To investigate whether acute stress caused by the Bam earthquake could alter the sex ratio at birth (SRB) 6–12 months later, the present study was done. The number of live births by sex was obtained from the National Organization for Civil Registration (Kerman province). The SRB was expressed as the male proportion. A prominent decline in the SRB (̃0·467) 11 months after the earthquake was observed (χ2=6·68, df=1, p=0·009). There was no significant difference between Bam and Kerman province (excluding Bam) for SRB (χ2=0·44, df=1, p=0·51) for a period of 33 month before the earthquake (from April 2001 to December 2003). It might be concluded that psychological tensions and stress are associated with a decrease in SRB.

In a sample of 282 marriages in New Nubia in Egypt, 39% were between first cousins and 21% between less closely related kin. The average number of liveborn offspring in first-cousin marriages was higher than in marriages between more distant relations and unrelated spouses, but the number of deaths among children of first-cousin couples was also higher.

Stroke is an emerging problem in sub-Saharan Africa, about which little is known since most research to date has been based on retrospective, hospital-based studies. This anthropological work, designed to complement a large community-based project on stroke incidence, focuses on local understandings and treatment-seeking behaviours in urban (Dar-es-Salaam) and rural (Hai) areas of Tanzania. Semi-structured interviews (n=80) were conducted with 20 stroke patients, 20 relatives of stroke patients, ten traditional healers, and 30 other local residents. In contrast to common expectations, and literature that finds witchcraft beliefs to be most common in rural areas, stroke in urban Dar was widely believed to emanate from supernatural causes (demons and witchcraft), while in rural Hai, explanations drew mostly on ‘natural’ causes (hypertension, fatty foods, stress). These different beliefs and explanatory models fed into treatment-seeking behaviours. The first option in Hai was hospital treatment, while in Dar-es-Salaam, where belief in demons led to hospital avoidance, it was traditional healers. In both sites, multiple treatment options (serially or simultaneously) were the norm. Analysis of patient and carer narratives suggested that causation beliefs outweighed other factors, such as cost and distance, in shaping effective treatment. Three policy implications are drawn. First, as other studies have also shown, it is important to engage with, rather than dismiss, local explanations and interpretations of stroke. Stroke awareness messages need to take into account the geographical and belief systems differences. Developing an understanding of explanatory models that recognizes that local beliefs arise from dynamic processes of social interaction will be critical to designing effective interventions. Second, there is a clear role for multiple healing systems with possibility of cross-reference in the case of a chronic, disabling condition like stroke, since biomedical treatment cannot offer a ‘quick fix’ while traditional healers can help people come to terms with their condition. Third, issues of communication between health services and their patients are particularly critical.

An adapted ‘sense of coherence’ scale short form (SOC-13) was administered in nine languages of Eritrea with a total of 265 participants (162 women and 103 men) in order to assess ‘resilience’ in quantitative terms. Statistical analysis yielded significant differences in SOC scores between the displaced and non-displaced: mean=54·84 (SD=6·48) in internally displaced person (IDP) camps, compared with mean=48·94 (SD=11·99) in urban and rural settlements (t=3·831, p<0·001). Post-hoc tests revealed that the main difference is between IDP camp dwellers and urban (non-displaced) residents. Those in rural but traditionally mobile (pastoralist or transhumant) communities scored more or less the same as the urban non-displaced – i.e. significantly higher than those in IDP camps (p<0·05). Analysis of variance showed that displacement has a significantly negative effect on women compared with men (RR=0·262, p<0·001). Repeating the analysis for the three groups confirmed that urban and pastoralist/transhumant groups are similar, while women in IDP camps are lower scoring (RR=0·268, p<0·001), Hamboka women being worst affected due to their experience of serial displacement. These findings are interpreted and discussed in the light of qualitative information gleaned from the study participants’ interrogation of the content of the SOC scale; and in the wider context of historical, socio-political and cultural characteristics of Eritrea. The study’s implications for humanitarian and public health policy are considered.

In January 1985, a Gallup poll sponsored by the American College of Obstetrics and Gynecologists reported that 76% of the US women sampled thought that there were substantial risks with using the pill, 31% thought the pill caused cancer and 64% thought the risk of childbearing was equal to or less than that in taking the pill. To assess the perceptions of the pill's safety internationally, a survey of 100–150 urban, middle-class women aged 18–45 years was conducted in each of eight countries in the developing world. There were striking similarities in perceptions of the pill's health effects between countries: (1) taking the pill is considered to have substantial health risks by 50–75% and is thought to be more hazardous than childbearing by over 40% of respondents except those in the African samples; (2) women who had used the pill are as unaware as those who had not of possible serious cardiovascular adverse effects; (3) the protective effects of the pill are virtually unknown; (4) the greatest inconsistency with scientific evidence concerns the risks of sterility and birth defects attributed to pill use. With information from this survey, family planning programmes can rectify almost universal misperceptions of the pill's safety when counselling new and continuing pill users.

Using data derived from the 1992–1993 National Family Health Survey, the sociodemographic characteristics of consanguineous marriage were determined in the Muslim population of India. In this nationally representative sample of 8436 women, consanguineous marriages accounted for 22·0% of the total. No differences between the consanguineous and non-consanguineous groups were observed in terms of mean age at marriage or mean age at cohabitation. The study confirmed the negative association between consanguineous marriage and maternal education but also indicated that women in consanguineous unions were more likely to be employed, albeit mainly in agricultural work on behalf of the family. Consanguineous couples more frequently lived in smaller towns and in an extended family environment. Somewhat conflicting results were obtained with indicators of socioeconomic status, but the overall picture suggested that consanguineous households had greater access to consumer goods because of their larger number of co-resident persons.