Sterilisation has been increasing in the United States in recent decades. Using the National Survey of Families and Households, this paper examines sterilisation among married couples using event history techniques, viewing husband and wife sterilisation as competing risks. Wives are more likely to experience sterilisation and at shorter durations of marriage. Number of children has a curvilinear effect on sterilisation, increasing and then decreasing its likelihood. Wives who are older than their husbands are more likely to get sterilised themselves. Black and Hispanic husbands are more likely to undergo sterilisation.

The exogenous cycles and population dynamics of the community at Penrith, Cumbria, England, have been studied (1557-1812) using aggregative analysis, family reconstitution and time series analysis. This community was living under marginal conditions for the first 200 years and the evidence presented is of a homeostatic regime where famine, malnutrition and epidemic disease acted to regulate the balance between resources and population size. This provides an ideal historic population for an investigation of the direct and indirect effects of malnutrition. Throughout the period studied, a short wavelength oscillation in grain prices was apparently the major external factor that drove exogenous cycles in mortality, birth rate, and migration. In particular, the different responses of children to variations in food supply are emphasised; fluctuations in poor nutrition correlated significantly with the variations in mortality rates for infants (probably indirectly during pregnancy and directly during the first year of life) and for young children (via susceptibility to lethal infectious diseases). Migratory movements contributed to the maintenance of homeostasis in the population dynamics. A medium wavelength cycle in low winter temperatures was associated with a rise in adult mortality which, in turn, promoted an influx of migrants into this saturated habitat. A model incorporating these interacting associations between vital events and exogenous cycles is presented: grain prices were an important density-dependent factor and constituted the major component of the negative feedback of this population and drove the exogenous, short wavelength mortality cycles. Cycles of births and immigration provide a positive feedback for the build-up of susceptibles and the initiation of smallpox epidemics and increased population size.

Using nationally representative data, it is shown that marital unions are relatively stable in Nigeria. Remarriage rates are high so little time is lost between unions. Consequently, the fertility of women who have experienced marital disruption is only slightly lower than for those in stable unions. Their slightly lower parity may be a function of a high incidence of reproductive impairment, which is a major reason for divorce and separation in Nigeria.

Some factors affecting marital distances have been studied in two Outer Hebridean islands, Harris (843 marriages) and Barra (444 marriages), over the period 1855-1990. In each island marital distances fell before 1900, but then rose to their greatest values after the 1950s. Fishermen generally married at the shortest distances and men in land-based occupations at the longest. The depression in the fishing industry during the 1880s and early 1890s was associated with reductions in marital distances, especially among fishermen. In the different regions of Harris, marital distances were least in the south-east, where settlement was most dense, and greatest in the south-west where it was most sparse.

When the association between marital frequencies and inter-settlement distances was studied, it was found that for Harris there was, overall, a trend to endogamous and short-distance marriage. However, this trend was only slight during 1955-90. For Barra a similar trend was found before 1955, but thereafter there appeared to be virtually no connection between marital frequency and inter-settlement distance. Thus the only constraint on marriage was the spatial distribution of settlements. In this situation the chances of random mating with respect to distance are maximised.

Application of ‘Central Place’ theory suggested that only since 1946 can any tendency be detected to regard Tarbert in Harris or Castlebay in Barra as Central Places, at least as far as marriage is concerned. In each island the tendency appears to be limited to the settlements closest to the Central Place.

This paper discusses ways in which empirical research investigating sexual networks can further understanding of the transmission of HIV in London, using information from a 24-month period of participant observation and 53 open-ended, in-depth interviews with eighteen men and one woman who have direct and indirect sexual links with each other. These interviews enabled the identification of a wider sexual network between 154 participants and contacts during the year August 1994-July 1995. The linked network data help to identify pathways of transmission between individuals who are HIV+ and those who are HIV−, as well as sexual links between ‘older’ and ‘younger’ men, and with male prostitutes. There appears to be considerable on-going transmission of HIV in London. The majority of participants reported having had unprotected anal and/or vaginal sex within a variety of relationships. The implications of these findings for policies designed to prevent the transmission of HIV are discussed.

This study reports an ecologic analysis of the relationship between mean birth weight (MBW) and nutritional, medical and social variables, using 1982 data for 47 prefectures in Japan.

Correlation analysis showed that variables that correlated significantly with MBW were mean temperature (r=0·63), total calorie intake (r=0·56), and body mass index of women (r=0·60). It is concluded that the MBW level in a given community represents the long and short term nutritional condition of mothers, and that the level may follow Bergman’s law: ‘In the same species, the body size of an animal increases along with latitude; that is, the lower the temperature, the larger the body size’.

Eight hundred and eighty-seven students from two major universities in Delhi, India, were surveyed, using a self-administered questionnaire, about their sexual knowledge, attitudes and behaviour. The data show that female students seem to be rejecting traditional Indian repressive sexual standards of premarital and non-procreative sex and the gender differences are beginning to narrow. Despite their sexual awareness, the students were highly ignorant of the facts of life. Being male and married did not make them more knowledgeable.

The effects of breast-feeding and supplementation practices on recent diarrhoea occurrence and stunted growth are modelled using logistic regression techniques. Data from the Demographic and Health Survey of Bolivia, 1989, show that, among children aged 3-36 months at the date of interview, the benefits of breast-feeding to child health were most pronounced among children living in rural poverty. Reduced breast-feeding among these children increased the likelihood of diarrhoea and stunted growth. In addition, the introduction of solid foods to currently lactating infants negatively influenced child health.

Amankwaa (1996) gives data on infant mortality in monogamous and polygynous families. However he does not categorise his data by sex. This is important because one might expect infant mortality to vary by sex; moreover the offspring sex ratios of polygynous and monogamous women reportedly differ.

James questions the validity of the very tentative statement made in the final sentence of our paper. Our claim concerned the proportion of twins in Britain in the 1990s that might have arisen through subfertility treatment and was linked to the s uggestion that the natural twinning rate might still be in decline. If this were true, we, like James, would regard that prospect with concern.

Murphy et al. (1997) showed age-standardised twinning rates for Scotland and England & Wales 1952–94. The rates declined to a value of about 9·2 per 1000 around 1978–81 and subsequently increased to about 11·5 per 1000 in 1992–94. The authors conclude their paper with the words: 'perhaps 15% of twins nationally now follow treatment and the natural twinning rate might still be in decline'.

Rao & DeMaris (1995) suggest that when age is controlled, cohabiting partners have higher coital rates than married partners. Their sample was restricted to couples whose relationships were of 5 years' duration or less. This restriction, according to the authors 'circumvents the confounding problem of age with duration of relationship'.