The building of dams to collect water for hydroelectricity and irrigation brings about environmental alterations and hence the appearance of a new ecosystem. These changes affect the human environment and result in demographic, social and economic alterations of the original settlements. In the mountainous regions of Palencia in the north of Spain, three dams have been built this century. This paper analyses the biodemographic modifications in the settlement directly affected by the construction of these dams, and compares it with nearby control settlements with similar demographic and social structure, in order to establish the effects of the flooding of extensive areas.

A prospective study of 113 children in rural Bhutan registered their morbidity and weight and their mothers' subsequent pregnancies, monthly for 32 months during the children's first 3 years of life. Children whose mothers had a subsequent birth interval of 18–30 months had an incidence of diarrhoea during the subsequent pregnancy 50% higher than their matched cohort whose mothers did not become pregnant (p=0·02). The relative risk for diarrhoea calculated from pooled child months was 1·51. Children whose mothers became pregnant also tended to have a higher incidence of skin infections.

Children, whose mothers were pregnant when they terminated breastfeeding, experienced an increased incidence of diarrhoea around weaning (p=0·01). Children weaned at the same age from non-pregnant mothers did not show increased morbidity.

This study, for the first time, relates observations of children's morbidity directly in time to the occurrence of the mother's subsequent pregnancy, and provides evidence of a causal relationship between a moderately short subsequent birth interval and a concurrent increase in morbidity for the study child.

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.

This study updates and extends estimates for unmet need and total demand for family planning for Jamaican women in the reproductive age group, 15–49. The findings suggest that, as yet unmet need for family planning was 22·7%, compared to 16% previously estimated.

This paper documents expectations of old age support in rural Nepal. Current living arrangements of the elderly have been analysed with a focus on the ownership of land holdings. It is argued that the inter-generational transfer of property through inheritance from the older to the younger generation, especially among sons, together with the Nepali normative prescription that sons care for their aged parents, provides a mechanism for old age support. However, land is becoming a scarce resource, cultural traditions are breaking down through modernisation and the living conditions of the elderly are likely to deteriorate as this process continues.

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.

Data on 2972 marriages in rural areas and 1180 marriages in urban areas of North Arcot Ambedkar district of South India, during 1982–88, were analysed. The mean age at marriage of females was 18·6 in the rural and 19·6 in the urban area. The proportion of females married before attaining the legal age of 18 years was higher among the rural community (36·8%) than in the urban community (28·9%). Univariate analysis revealed an association between early age at marriage and the socioeconomic variables religion, caste, consanguinity, marital distance, spousal age difference, education and occupation of both bride and bridegroom, and socioeconomic status of the family. Multivariate analysis showed an independent relationship of marital distance and bridegroom's occupation with early age at marriage of females in the rural area alone and the bridegroom's education in the urban area alone. Consanguinity, spousal age difference and bride's education were found to be independently related with early age at marriage of females in both rural and urban areas.

In populations in which the frequency of illegitimacy is high, illegitimates and legitimates may be subjected to different demographic and social pressures, with social and genetic consequences. A rural population from north-east Portugal is studied and variables from birth, marriage and death records are compared according to the legitimacy of the individuals. The analysis shows important differential demographic patterns in infant and child mortality and in migration prior to and related to marriage, especially in women. Some changes over time and gender differences are also evident.

Estimates of fertility in Protestant Barra and Catholic Harris, islands in the Outer Hebrides, over the period 1856–1985, show that in both islands fertility declined, although marital fertility was generally greater than in Scotland as a whole, and illegitimate fertility was less. However, in Barra during 1966–75 there were pronounced rises in all the indices; illegitimate fertility showed the smallest rise. The publication of the papal encyclical Humanae Vitae may have played a part in this change in fertility, although other, probably local, factors must have been acting, as the first rise in numbers of births occurred before the publication of the encyclical. Other than this transient rise, the religious difference between Harris and Barra had little effect on changes in fertility over the whole period.

Indices of proportions married showed declines until after World War 2, followed by steep increases. The marked decline in fertility in both islands may be due in part to this low nuptiality. In addition, a trend of occupation away from traditional crofting and fishing towards more skilled mercantile and professional employment may have played a role.

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.

Using responses from questions about age at first sexual intercourse and age at first marriage, this paper offers a method of studying premarital sexual behaviour in societies where the subject is a taboo topic. More than half of the currently married women in Kinshasa engaged in sexual intercourse before marriage. The likelihood of having premarital intercourse increases among younger women, those with higher education, and those whose ethnic groups have liberal attitudes towards sexual conduct. The results also suggest that sexual activity accounts for late marriage.

This study examines the relationships between consanguineous marriages and marriage payment, using data from two Muslim qaums living in urban and rural areas in Aligarh District, Uttar Pradesh, North India. Qaum and locality were found to have no significant association with the dowry system. Marriage payment is less common in consanguineous than in non-consanguineous marriages. However, the association between marriage payment and the type of marriage is significant at p<0·001. The dowry system is more prevalent among the higher socioeconomic groups, while the bride-wealth system is more common among the lower socioeconomic groups.

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.

Despite the absence of a family planning programme, the prevalence of sterilisation in Brazil has increased substantially, such that it is used by relatively young women in poor areas of the country. Sterilisation is influenced more by the characteristics of the health service than by socioeconomic characteristics of the population.

The relationship between sleep habits and psychosomatic health complaints was investigated by a questionnaire study in 148 bank workers in Tokyo. Daily bedtime was more flexible than daily rising time, and both mean bedtime and rising time tended to be earlier with increasing age. Multiple logistic regression analysis showed that psychosomatic health complaints of sleep disturbances, fatigue, digestive troubles, and depressive mood were significantly associated with sleep habits and perceived mental stress.

The 1988 Malawi Traditional and Modern Methods of Child Spacing Survey data are used to identify determinants of infant mortality in Malawi. The logistic binomial analysis shows that socioeconomic factors are significant even during the neonatal period while the length of the preceding birth interval is significant in the post-neonatal period only. There is a strong familial correlation of mortality risks during both the neonatal and post-neonatal periods but the effect of geographical area of residence is stronger in the post-neonatal period.

This paper conceptualises the motive force behind human childbearing as originating in two broad traits which have biological bases, are shaped by experiences during early life and are expressed through their effect on desires and intentions. An instrument for measuring childbearing motivation, the Childbearing Questionnaire (CBQ), is presented. Using a sample of 401 married couples two main scales, nine subscales, and several independent items are described. Evidence for the reliability and validity of this instrument is presented. The versatility of the CBQ as a research instrument and the usefulness of the conceptualisation from which it is derived as a way of integrating social, behavioural, and biological science approaches to childbearing motivation are discussed.

This study uses data from thirteen Demographic and Health Surveys to examine effects of female migration on fertility in African cities. Contrary to expectations, migration from villages and towns in the 1980s and 1990s reduced total fertility rates in African cities by about one birth, from an estimated average of 5·55 in the absence of migration to 4·59. New arrivals experience much lower fertility in their first few years in cities than long term residents of similar age and parity. This results from the initial unmarried status of most migrants, high levels of spousal separation among new arrivals who are married, dramatic increases in use of modern methods of contraception after 2 years in cities, and continuation of traditionally long durations of postpartum abstinence. Accomodation of additional migrants thus appears consistent with efforts to reduce fertility in cities. Moreover, prospects for increased contraceptive prevalencein Africa may depend heavily on changes in population distribution that influence the demand for children, specifically movement to cities.

Urinary cortisol and adrenaline excretion rates were measured in three Australian Aboriginal communities in the Kimberley region in the north-west of the country. The three communities, Derby, Kalumburu and Kupungarri, differ in size and remoteness and some lifestyle parameters. Cortisol excretion rate is associated with age and urine flow rate, but there is no association with smoking or the consumption of alcohol. All three communities show very high cortisol excretion rates compared to a sample of UK (Oxford) residents and there are also differences between the three communities. Adrenaline excretion rate also shows associations with age and urine flow rate, but not with smoking. Aboriginal people in the Kimberley region excrete adrenaline at a slightly higher rate than that found in Oxford, which itself is high by world standards. There are no marked differences between communities in their adrenaline excretion rates. Alcohol drinkers in Derby, where alcohol is freely available, have higher adrenaline output than non-drinkers.