Evolutionary theory suggests that maternal grandparents will invest more in their grandchildren than paternal grandparents, due to the difference between the certainty of maternity and the uncertainty of paternity. Most tests of this prediction have tended to use retrospective ratings by grandchildren rather than examining grandparental behaviour. Using a large-scale data set from the UK (n>7000), significant differences are shown between maternal and paternal grandparents in terms of frequencies of contact with their newborn grandchildren, while controlling for a wide range of other variables. Maternal grandparents also provided a significantly wider range of financial benefits than paternal grandparents. Maternal grandparents were also more likely to provide essentials and gifts and extras for the baby. Multiple correspondence analysis showed that contact frequencies systematically related to other measures of grandparental investment, indicating that contact frequencies are a useful proxy measure to examine overall investment. Findings are discussed with reference to the paternity uncertainty hypothesis.

This study sought to determine which factors among the indicators of socioeconomic status have the most influence on physical, mental and social functions, and on subjective well-being, all of which are components of successful ageing. A representative random sample of 1825 persons aged 65 years or older was surveyed by face-to-face interview. Socioeconomic status was measured by educational level, family household income, personal income and property ownership. The factors measured were chronic diseases, activities of daily living (ADL) for physical functioning, history of mental disease, Mini-Mental Status Examination questionnaire (MMSE) scores for mental functioning, social activity participation per week for social functioning, and the Philadelphia Geriatric Center Morale Scale (PGCMS) for subjective well-being. Multiple logistic regression analyses were performed. Education level was the most important factor in physical and mental functioning, whereas personal income was the most important in social functioning. Educational level, household income and personal income were significantly associated with subjective well-being as assessed by PGCMS scores. Subjects who demonstrated successful ageing were more likely to have a higher education and higher personal income. The results point to the importance of focusing on disparities in each component of successful ageing, which may point to appropriate health-promotion strategies for eliminating inequality in successful ageing.

Daily luteal progesterone levels were measured for 124 regularly menstruating women, aged 18–44, by radioimmunoassay of steroid levels in saliva. A consistent pattern of age variation in luteal function was found, with the lowest levels of progesterone in the 18–19-year-old and 40–44-year-old groups, the highest values in the 25–34 year olds, and intermediate values in the 20–24 and 35–39-year-old groups. The striking similarity of this pattern of age variation with empirically and theoretically generated curves of apparent fecundability, suggests that age-related changes in ovarian function may underlie observed age variation in fecundability.

A group of 239 mothers breast-feeding on leaving hospital were followed up 6 months later by a postal questionnaire; 216 (90%) responded and, of these, 41% had discontinued breast-feeding before the end of the 12th week, the greatest decline occurring within the first 6 weeks. Duration of breast-feeding was significantly influenced by social class and, for parous mothers, previous breast-feeding success. Seventy-two per cent of the mothers who stopped breast-feeding within the first 12 weeks gave inadequacy of the milk supply or an unsettled baby as contributory reasons. Maternal fatigue and painful nipples were the other two most frequent contributory problems. Only 6% of all the mothers admitted to not having enjoyed breast-feeding. The person most commonly consulted about breast-feeding problems was the health visitor. Regardless of how long they had breast-fed, 43% of the mothers would have liked more help.

Using retrospective individual mortality records of three cohorts of newborns (1954–1958, 1959–1962 and 1963–1967) from a large national fertility survey conducted in 1988 in China, this paper examines the effect of being conceived or born during the 1959–1961 Great Leap Forward Famine on postnatal mortality. The results show strong evidence of a short-term (period) effect of the famine, caused directly by starvation or severe malnutrition during the period of the famine. After controlling for period mortality fluctuation, however, the famine-born cohort does not show higher mortality than either the pre-famine or the post-famine cohort. Aggregate-level cross-temporal comparisons using published cohort population counts from China's 1982 Census, 1990 Census, 1995 micro-Census, 2000 Census and 2005 micro-Census lead to the same conclusion. The relevance of these new findings for the ‘fetal origins’ hypothesis and the selection effect hypothesis is discussed.

Over the course of the 20th century the sex differential in life expectancy at birth in the industrialized countries has widened considerably in favour of women. Starting in the early 1970s, the beginning of a reversal in the long-term pattern of this differential has been noted in some high-income countries. This study documents a sustained pattern of narrowing of this measure into the later part of the 1990s for six of the populations that comprise the G7 countries: Canada, France, Germany, Italy, England and Wales (as representative of the United Kingdom) and USA. For Japan, a persistence of widening sex differences in survival is noted. The sex differences in life expectancy are decomposed over roughly three decades (early 1970s to late 1990s) from the point of view of four major cause-of-death categories: circulatory diseases, cancers, accidents/violence/suicide, and ‘other’ (residual) causes. In the six countries where the sex gap has narrowed, this has resulted primarily from reduced sex differences in circulatory disease mortality, and secondarily from reduced differences in male and female death rates due to accidents, violence and suicide combined. In some of the countries sex differentials in cancer mortality have been converging lately, and this has also contributed to a narrowing of the difference in life expectancy. In Japan, males have been less successful in reducing their survival disadvantage in relation to Japanese women with regard to circulatory disease and cancer; and in the case of accidents/violence/suicide, male death rates increased during the 1990s. These trends explain the divergent pattern of the sex difference in life expectation in Japan as compared with the other G7 nations.

Several studies have found relationships between early life factors (birth weight, length of gestation, height, weight, duration of breast-feeding, maternal age, social class, periods of infection, presence of adverse life events, and quality of housing conditions in childhood) and age at menarche but none has considered all of these factors in the same study. The follow-up study of the Newcastle Thousand Families birth cohort, established in 1947, provided age at menarche data collected retrospectively at age 50 from 276 women who returned self-completion questionnaires in 1997. Three main independent associations were observed: girls who experienced a shorter gestation, girls whose mothers were younger when they were born, and girls who were heavier at age 9 had earlier menarche. Birth weight, standardized for gestational age, was found to have different relationships with age at menarche depending upon how heavy or light a girl was at age 9. The results of this study support the hypotheses that conditions in fetal and early life are associated with the timing of menarche and that greater childhood growth is associated with earlier menarche. It is suggested that future work should focus on illuminating the mechanisms underlying these statistical relationships.

Data from a national representative sample of 1023 elderly and near-elderly Taiwanese were used to explore whether allostatic load is associated with health outcomes and mediates the association between socioeconomic status and health in a non-Western population. The information collected included: demographic characteristics; allostatic load scores; socioeconomic status, measured by education and income; health behaviours; health-related variables, including self-rated health, basic activities of daily living difficulties, instrumental activities of daily living difficulties, and physical activity difficulties. The adjusted prevalent odds ratios of higher allostatic load level were 1·25 (95% CI: 1·00, 1·56) for reporting one level worse in self-rated health and 1·43 (95% CI: 1·14, 1·82) for reporting one more physical activity difficulty. There were significant associations of lower education or less income with worse self-rated health and more difficulties with physical functioning. The associations between education, income and health status are not mediated by the conventional ten-point measure of allostatic load in older Taiwanese adults.

Although health is generally believed to improve with higher wealth, research on HIV in sub-Saharan Africa has shown otherwise. Whereas researchers and advocates have frequently advanced poverty as a social determinant that can help to explain sub-Saharan Africa's disproportionate burden of HIV infection, recent evidence from population surveys suggests that HIV infection is higher among wealthier individuals. Furthermore, wealthier countries in Africa have experienced the fastest growing epidemics. Some researchers have theorized that inequality in wealth may be more important than absolute wealth in explaining why some countries have higher rates of infection and rapidly increasing epidemics. Studies taking a longitudinal approach have further suggested a dynamic process whereby wealth initially increases risk for HIV acquisition and later becomes protective. Prior studies, conducted exclusively at either the individual or the country level, have neither attempted to disentangle the effects of absolute and relative wealth on HIV infection nor to look simultaneously at different levels of analysis within countries at different stages in their epidemics. The current study used micro-, meso- and macro-level data from Demographic and Health Surveys (DHS) across 170 regions within sixteen countries in sub-Saharan Africa to test the hypothesis that socioeconomic inequality, adjusted for absolute wealth, is associated with greater risk of HIV infection. These analyses reveal that inequality trumps wealth: living in a region with greater inequality in wealth was significantly associated with increased individual risk of HIV infection, net of absolute wealth. The findings also reveal a paradox that supports a dynamic interpretation of epidemic trends: in wealthier regions/countries, individuals with less wealth were more likely to be infected with HIV, whereas in poorer regions/countries, individuals with more wealth were more likely to be infected with HIV. These findings add additional nuance to existing literature on the relationship between HIV and socioeconomic status.

This study, conducted in Kisumu District, Kenya, identified important risk factors for infection with intestinal helminths using traditional epidemiological methods. This was combined with a rapid assessment study using qualitative methods, which focused on sanitation practices and local illness perceptions. The multiple logistic regression analysis revealed that the absence of latrines was a significant predictor for hookworm infection with an odds ratio (OR) of 1·9. The analysis also revealed that households without soap had a 2·6 times higher risk of being infected with Ascaris lumbricoides compared with households where soap was available, and that the number of inhabitants living in a household was a significant predictor for infections with hookworms (OR=3.2). Furthermore, the presence of children of 5 years and under in the household was a predictor for infection with A. lumbricoides (OR=2.7), while the absence of this age group was a predictor for hookworm infection (OR=3.8). The qualitative part of the study revealed that people did not consider worms as a serious health threat, but as a nuisance. Among the population, latrines were seen as beneficial because they were believed to prevent disease, to provide privacy and to keep the environment free of faeces. Handwashing was done many times a day but usually not with soap, which was mainly used when bathing or washing the whole body. Many inhabitants in a household or the presence of children of 5 years and under were never mentioned as being a disadvantage, and these elements would therefore be difficult to include in a control strategy. Since the lack of latrines and of soap were identified as risk factors for infection, while latrines, soap and medicine were seen as assets by the population, it is suggested that helminth control interventions should be concentrated within these areas in this particular society.

The social environment and exposure to life challenge affect a person's physical and emotional well-being. The present research uses a population-based study of the elderly in Taiwan to elaborate the cumulative physiological costs – as reflected in biological markers of risk factors known to have adverse consequences for health – of challenge and unfavourable position in social hierarchies and networks. Overall, biological markers of risk among the elderly are similar in Taiwan and the United States. However, male and female Taiwanese elderly are at lower risk for illness associated with indicators of DHEA-S, while women are at higher risk for illness associated with elevated blood pressure, and men at lower risk for illness associated with total/HDL cholesterol, and glycosylated haemoglobin. There are strong and statistically significant effects of position in social hierarchy (education) and challenge (recent widowhood and a perception of high demands) on an index of cumulative risk (allostatic load). Membership in social networks and participation in social activities have expected, but not statistically discernible, effects.

There is an abundant literature on the relationship between women’s education and maternal and child outcomes, including antenatal and postnatal care, onset of antenatal care and skilled birth attendance. However, few studies have adopted the ‘equity’ lens, despite increasing evidence that inequities between rich and poor are increasing although maternal and child mortality is declining. This study examined the differential effects of women’s education within different socioeconomic strata in Africa. The most recent Demographic and Health Surveys (DHS) conducted in the Democratic Republic of the Congo, Egypt, Ghana, Nigeria and Zimbabwe were used. In each country, the original sample was stratified into three socioeconomic groups: poor, middle and rich. For each maternal health service utilization variable, the gross and net effects of women’s education, controlling for age, parity, religion, marital status, health insurance, access to health facilities, partner’s education and current place of residence, were estimated using logistic regression, taking into account the complex sampling design of the DHS. The findings revealed country-specific variations in maternal health service utilization, and for most indicators there was a clear gradient among socioeconomic strata: women living in better-off households exhibited greater access to, and utilization of, maternal health services. Multivariate analyses revealed that women’s education had a positive association with type of antenatal care provider, timing and frequency of antenatal care visits, place of delivery and presence of a skilled birth attendant at delivery. Many other factors were found to be significantly associated with maternal health service utilization. For instance, parity had a negative and significant association with timing of first antenatal care visit. Likewise, partner’s education was positively and statistically associated with timing of first antenatal care visit. It is argued that an over-generalization of the association between women’s education and maternal health service utilization can be misleading. Efforts to improve maternal health service utilization in Africa must adopt an ‘equity’ approach, taking into account the specific needs of sub-populations.

Data from the District Level Household Survey (2002) conducted by the Reproductive and Child Health Project in India has been used to examine the impact of utilization of antenatal care services on improvement in maternal health in rural areas of Uttar Pradesh, India. Multilevel analysis shows that after controlling for other socioeconomic and demographic factors, utilization of antenatal care services may lead to the utilization of other maternal health related services such as institutional delivery, delivery assisted by trained professionals, seeking advice for pregnancy complications, and seeking advice for post-delivery complications. There is strong clustering of utilization of services within the primary sampling units (i.e. villages) and districts.

The effects of infant suckling patterns on the post-partum resumption of ovulation and on birth-spacing are investigated among the Gainj of highland New Guinea. Based on hormonal evidence, the median duration of lactational anovulation is 20·4 months, accounting for about 75% of the median interval between live birth and next successful conception (i.e. resulting in live birth). Throughout lactation, suckling episodes are short and frequent, the interval changing slowly over time, from 24 minutes in newborns to 80 minutes in 3-year olds. Maternal serum prolactin concentrations decline in parallel with the changes in suckling patterns, approaching the level observed in non-nursing women by about 24 months post-partum. A path analysis indicates that the interval between suckling episodes is the principal determinant of maternal prolactin concentration, with time since parturition affecting prolactin secretion only in so far as it affects suckling frequency. The extremely prolonged contraceptive effect of breast-feeding in this population thus appears to be due to (i) a slow decline in suckling frequency with time since parturition and (ii) absence of a decline over time in hypothalamic–pituitary responsiveness to the suckling stimulus.

A biosocial model of the effects of early adolescent testosterone levels and religiosity on adolescent males' sexual attitudes and activity over a 3-year period was examined. Using panel data for approximately 100 boys who were 12·5/13·0 years old at study entry, significant additive effects of free testosterone and frequency of attendance at religious services were demonstrated on the transition to first intercourse and other aspects of sexual behaviour and attitudes. No interactive effects of the two predictors were found. Boys with higher free testosterone levels at study entry who never or infrequently attended religious services were the most sexually active and had the most permissive attitudes. Boys with lower free testosterone who attended services once a week or more were the least active and reported the least permissive attitudes. For some behaviours, differences between free testosterone/attendance groups increased over time, resulting in substantial behavioural differences by the final round of measurement 3 years later.

There is increasing evidence that age at menarche has decreased in Europe and the United States during the last century and in Japan over the last several decades. Data from a community-based survey conducted in two rural counties of Anhui Province in China indicate a similar, downward secular trend in age at menarche for Chinese women. The present study shows the mean age at menarche decreased by 2·8 years, from 16·5 to 13·7, over an approximate 40-year time interval. This rapid decrease in age at menarche may partly be due to better nutrition and living standards reflected by the improved socioeconomic standards experienced in China over the past few decades. To test this hypothesis, a number of determinants of age at menarche were assessed; year of birth, literacy status, county of residence, amount of physical labour, general health status, pesticide exposure before age at menarche, and drinking water source were all found to be associated with age at menarche.

Fisher (1930) presented both theoretical and empirical results concerning genetic influences on fertility. Since then, only sparse research has been done on the genetics of fertility, although more sophisticated methodogy and data now exist than were available to Fisher. This paper presents a behavioural genetic analysis of age at first intercourse, accounting for genetic, shared environmental, and selected non-shared environmental influences. The data came from the nationally representative National Longitudinal Survey of Youth (NLSY). A newly developed kinship linking procedure was used that identifies links for cousins, half-siblings, full-siblings and twins in the NLSY. The results suggest a genetic influence in the overall dataset, and also among whites and in male–male and opposite-sex pairs. Genetic influences were extremely small or non-existent for blacks and for female–female pairs. Shared environmental influences were small for most subsets of the data, but moderate for female–female pairs. Two specific non-shared environmental influences – self-esteem and locus of control – were ruled out as accounting for any meaningful variance, although other general sources of non-shared environmental influence appear potentially important. Analysis of selected samples from upper and lower tails suggested that genetic influences are important in accounting for both early and late non-virginity. These findings are consistent with work reported by Miller et al. (1999), who used molecular genetic methods. Generally, these findings support the existence of genetic influences and implicate non-shared environmental influences as being important determinants of the timing of loss of virginity among US adolescents and young adults.

Forty-five per cent of first marriages in Ethiopia end in divorce within 30 years, and two-thirds of women who divorce do so within the first 5 years of marriage. This paper looks at two factors that may have an impact on the risk of divorce in Ethiopia: early age of first marriage, and childlessness within the first marriage. Data used were from the 1990 National Family and Fertility Survey conducted by the Government of Ethiopia. A total of 8757 women of reproductive age (15–49) were analysed. Life table analysis was used to determine the median age at first marriage, first birth and the median duration of marriage. Cox models were analysed to determine the differentials of divorce. The results of this analysis showed that both early age at marriage and childlessness have a significant impact on the risk of divorce. An inverse relationship was found between age at marriage and risk of divorce. Having a child within the first marriage also significantly reduced the risk of divorce. In addition, several cultural and socioeconomic variables were significant predictors of divorce.

From 1971 to 1984, the Israeli Defence Forces administered two tests unaltered that qualify as IQ tests. These were the Matrices and the Instructions tests. The former is an adaptation of Raven's Progressive Matrices, similar to the original in that there are clusters with progressive difficulty and an escalation of difficulty throughout the test. The raw score range is from 4 to 35. The Instructions test is adapted from the old US Army Alpha Instructions Test and is described as an Otis-type verbal test. It includes 21 open-ended instructions. Typical items: write the last letter of the word which is the opposite of black; write the third letter of the largest word among the following four words; find the word beginning and ending with the same letter and write that letter. There are similar questions using numbers rather than letters. Both tests are timed, and most subjects do not complete either. There is no penalty for wrong answers (Col. Moshe Even-Chen, personal communication, 14 March 1990; Gal, 1986, pp. 79 and 95; Judy Goldenberg, personal communications, 4 March 1991 and 25 April 1993).

The perspectives of mothers-in-law about intra-household decision-making, family size and family planning are investigated, and their views compared with those of their sons and daughters-in-law. Women (717 daughters-in-law), their husbands (717 sons) and their 522 mothers-in-law were interviewed in eight squatter settlements in Karachi, Pakistan. Decisions about the schooling and health care of children, and the purchase of jewellery, are perceived to lie within the nuclear family domain (i.e. husband and wife). There was a difference in mothers-in-law’s, daughters-in-law’s and sons’ desire to have more children. Twenty-eight per cent of mothers-in-law versus 58% of daughters-in-law did not want more grandsons/sons and 36% of mothers-in-law versus 66% of daughters-in-law did not want more granddaughters/daughters. The difference was markedly greater among the mother-in-law/daughter-in-law pairs than in the mother/son pairs. Overall, the mother-in-law’s role seems to be somewhat overshadowed by that of her son (family male member), except for limiting family size. It is suggested that mothers-in-law should be included in Information–Education–Communication (IEC) campaigns about family planning.