The hypothesis that psychological stress during early childhood leads to advanced reproductive maturation was assessed using data from the California Childhood Health and Development Study. Regression analyses failed to indicate that bed wetting, nightmares or thumb-sucking at age 5 predict age at menarche, regardless of controls for mother's age at menarche. Among socioeconomic variables suggested as contextual stressors measured at age 9–11 only mother's education was a significant predictor of daughter's age at menarche, though its effect is trivial compared to mother's age at menarche. Path analysis on a subsample of the subjects failed to demonstrate the hypothesised indirect effect of mother's age at menarche on daughter's age at menarche acting through early marriage and marital dissolution. These results cast doubt on the theory that early childhood stress is the key to divergent reproductive strategies among females based on the timing of reproductive maturation.

Coital frequency is studied among couples as a function of marital or cohabiting status, relationship duration, number of children, religious affiliation, income, education, fertility intentions, age, race, self-assessed health, time spent in work, and perceived relationship quality. Data are from the 1987–88 National Survey of Families and Households. Predictors of coital frequency that were stable across several analyses were male's and female's ages, the duration of the relationship, and the male partner's self-assessed health. When the discrepancy in partners' reports was adjusted, cohabitation status, number of children, future fertility intentions, religious affiliation, and relationship quality as assessed by the female partner were significant. The results suggest a substantial idiosyncratic component to the determination of coital frequency in relationships.

The influence of ethnicity on obstetric performance in Singapore was assessed by retrospective analysis of all deliveries in the National University Hospital over a 7-year period. Malay mothers were younger, shorter, less educated, of higher parity, were more likely to have had no antenatal care, and had the highest incidence of premature labour. However, mothers of Indian origin had the smallest babies, the highest incidence of low birth weight and significantly higher perinatal mortality rates. Chinese mothers fared better than their Malay and Indian counterparts in all parameters assessed. The ethnic origin of the mother has an important bearing on perinatal performance. This emphasises the importance of designing appropriate strategies to improve perinatal health in the different ethnic groups.

This paper compares levels and trends of population growth rates, age and sex composition, mortality, and fertility including family planning practices in the world's two most populous countries, China and India. Both countries are undergoing demographic transition but China is nearer than India to achieving a stationary population. Fertility in China has declined below replacement level while in India it is nearly one and a half children per woman above replacement level. Both countries have achieved large reductions in mortality but life expectancy at birth in China is currently about 10 years longer than in India. Both countries have young populations but China will precede India in the aging of population structure during the 21st century.

Infant and child mortality levels and trends in Bangladesh are examined using data from the 1989 Bangladesh Fertility Survey. Both infant and child mortality declined from the mid 1970s but infant mortality declined more quickly. The level of infant mortality in 1989 was around 100 per 1000 live births while child mortality (5q) was 200 per 1000 live births. Life table analysis confirms the change in infant and child mortality.

The decline in infant mortality is attributed to the introduction of improved public health measures and access to maternal and child health services.

This study investigates the dimensions of occupation, and distances between occupational categories, by using intra-pair differences in adult occupational position for identical twins reared apart. Status and farm dimensions of occupation were identified. The results validate the use of occupational status as a dimension of occupational position. The causes of individual differences for the derived status dimension were also evaluated, based on groups of identical and fraternal twins reared apart or together. Genetic effects accounted for a substantial amount of the variance in occupational status for men, while shared and non-shared environmental effects were of about equal importance. For women, genetic effects were less important, and shared and non-shared environmental effects accounted for more of the variation. The results confirm that genetic effects are important sources of the familial resemblance often found for occupational status for men.

From marriage records of a Northern Portuguese parish for 1900–80, endogamy and exogamy rates were calculated for birthplace and residence in order to analyse the effect of industrialisation on the population structure after 1940. Marriages that were endogamous relative to birthplace decreased between 1940–49 (58·9%) and 1988 (20·5%), while exogamy increased. Exogamous marriages in which people came from outside the municipality (51·92%) were greater than those of the surrounding region (42·04%). After industrialisation, the pattern of marriages changed for residence, with an increase in the number of individuals who came from the district to work in the factories and married. Industrialisation advanced the start of exogamy which, for most Portuguese populations, began later, in the 1960s.

Changes in body weight were examined for non-pregnant women in rural Nepal, using 183 anthropometric measures between the early winter and monsoon seasons in 1982, 1982–83, 1990–91 and 1993. The women gained weight when work loads decreased after the monsoon, but despite substantial changes in total energy expenditure, which were out of phase with changes in food intake, seasonal changes were small, averaging only up to 2.6% of initial body weight.

There were notable differences between individual women, changes in body weight ranging from-5·6 kg to 4·8 kg. Weight change was examined with respect to lactation status, age, body mass index, mid upper arm circumference and skinfolds as well as total energy expenditure and intake. Non-lactating women, very thin women and women aged under 25 years gained more weight than their counterparts, both before and after the monsoon. Data for a sub-sample in 1982–83 indicated that women who maintained high physical activity levels throughout the year were less prone to weight loss than women whose activity fluctuated between seasons. Initial energy reserves, age-related maturation factors, levels of physical activity and energy intake combine to produce the notable inter-individual variation in body weight changes observed in this population.

Effective community based malaria control programmes require an understanding of current perceptions of malaria as a disease and its severe manifestations. Quantitative and qualitative surveys of mothers on the Kenyan Coast suggest that fever is conceptualised in biomedical terms whereas the aetiology of severe malaria is perceived to be of more complex cultural origin. This is reflected in the treatments sought for convulsions. The results are discussed in the context of ethnographic factors. To be effective, future health information programmes must take cultural beliefs into account.