There is a general consensus in the literature that fertility differences between populations can be accounted for by differences in just four key proximate determinants: nuptiality, the postpartum non-susceptible period, contraception and abortion. Natural fecundibility is generally assumed to be constant between populations. This paper puts the theoretical and empirical case for a re-evaluation of that assumption, drawing on the under-utilized data on sexual activity collected in the Demographic Health Surveys (DHSs). Using data for married women in nine African countries, the analysis finds substantial population level differences in mean monthly coital frequency, which, if accurate, suggest an important demographic effect. There is a clear regional patterning to these differences, with levels of activity considerably lower among women in the West African populations included in the study than those from East and southern Africa. For West Africa in particular the data indicate the normality of exceptionally long periods of very infrequent or no intercourse by married women outside the period of postpartum abstinence. The findings challenge prevailing presumptions concerning susceptibility to pregnancy in marriage on which statistics for unmet need for family planning are derived. While doubts are raised over the precision of the sexual activity data used, the paper argues for the need for a greater effort to operationalize the ‘proximate determinant of conception’, not only for more accurate fertility modelling, but also as a planning tool for a more sensitive provision of family planning services in Africa.

This paper examines whether low income is a barrier to contraceptive use in Pakistan, a country in which economic conditions are deteriorating at a time when the private sector is becoming a more important supplier of contraception. Multivariate regression analysis performed using the Pakistan Contraceptive Demand Survey suggests that low income is a deterrent to modern contraceptive use in Pakistan. This is particularly the case for contraceptive methods supplied through the private sector. It is concluded that, if the aim of family planning programmes is to reach low-income people, the prices of contraceptives supplied through the private sector should be kept as low as possible.

Research designs to study alcohol use and abuse have included twin, adoption and family history/high risk studies. Results have consistently implied a genetic factor in the aetiology of alcohol abuse. However, less research has been conducted in search of environmental factors. This study uses kinship structure in a large national dataset (the National Longitudinal Survey of Youth) to estimate (using DeFries–Fulker analysis) the extent of the shared genetic, non-shared genetic, shared environmental and non-shared environmental influences on alcohol use. The NLSY kinship sample contained 3890 pairs of cousins, half-siblings, full-siblings and twins between the ages of 14 and 21 in the initial year of the survey (1979). Estimates of heritability (h2) and shared environment (c2) were small to moderate for the entire dataset for both light drinking and heavy drinking behaviour, with h2 estimates slightly higher in each case. Non-shared genetic measures of self-esteem and locus of control accounted for a significant portion of the remaining variance in heavy drinking behaviour. Race and gender patterns showed c2 and h2 estimates that were also small to moderate for both light and heavy drinking behaviour. Significant non-shared effects were found for the White group for heavy drinking behaviour, and for male pairs for both heavy and light drinking behaviour. Additionally, implications and future directions are discussed.

Indirect estimates of maternal mortality in India indicate that fertility decline has reduced maternal deaths by reducing the frequency of pregnancy and childbirth. The earlier stages of fertility decline are also likely to have lowered maternal mortality by reducing the risk of pregnancy and childbirth as the proportion of births among risky multiparous, older women declines. However, further fertility decline may well be associated with some increase in risk. Risk will also remain high if the health status of Indian girls and women remains poor. This study uses a sample of maternal deaths and deliveries among patients who survived which occurred in Civil Hospital, Ahmedabad, Gujarat during 1982–1993 to investigate these issues further. The women in the sample have relatively low fertility and represent a fairly late stage of fertility decline. They also have persistently poor health status. Logit regression analysis reveals that although fertility decline is associated with some increase in risk, poor health status is the more important maternal mortality risk factor. Without attention to female health, even childbearing among expectant mothers with low fertility continues to be hazardous.

Child mortality differentials according to water supply and sanitation in many urban areas of developing countries suggest that access to piped water and toilet facilities can improve the survival chances of children. The central question in this study is whether access to piped water and a flush toilet affects the survival chance of children under five in urban areas of Eritrea. The study uses data collected by the Demographic and Health Survey (DHS) project in Eritrea in 1995. The results show that while the unadjusted effect of household environment (water supply and toilet facility) is large and statistically significant during the post-neonatal and child periods, it is relatively small and statistically insignificant during the neonatal period. The effect of household environment remains substantial during the post-neonatal and child periods, even when other socioeconomic variables are held constant. However, the household environment effect totally disappears during the neonatal period when the socioeconomic factors are controlled for.

Nuptiality norms in rural Bangladesh favour birth during the teenage years. An appreciable proportion of teenage births are, in fact, second births. This study examines the relationship between teenage fertility and high infant mortality. It is hypothesized that if physiological immaturity is responsible, then the younger the mother, the higher would be the mortality risk, and the effect of mother's ‘teenage’ on mortality in infancy, particularly in the neonatal period, would be higher for the second than the first births. Vital events recorded by the longitudinal demographic surveillance system in Matlab, Bangladesh, in 1990–92 were used. Logistic regression was used to estimate the effects on early and late neonatal (0–3 days and 4–28 days respectively) and post-neonatal mortality of the following variables: mother's age at birth, parity, education and religion, sex of the child, household economic status and exposure to a health intervention programme.

The younger the mother, the higher were the odds of her child dying as a neonate, and the odds were higher for second children than first children of teenage mothers. First-born children were at higher odds of dying in infancy than second births if mothers were in their twenties. Unfavourable mother's socioeconomic conditions were weakly, but significantly, associated with higher odds of dying during late neonatal and post-neonatal periods. The results suggest that physical immaturity may be of major importance in determining the relationship between teenage fertility and high neonatal mortality.

Women in India suffer from a high incidence of reproductive disease, disability and death. Very little work has been done on men, but a much higher incidence of sexual experience outside marriage and sexually transmitted diseases (STDs) among males than previously expected for this population is now being documented. In north India, women are dependent on their husbands and other family members for health-related decisions. Therefore, the behaviour, knowledge and attitudes of men are integral to the reproductive health status of couples there. This study explores knowledge about three distinct areas of reproductive health among 6549 married men in five districts of the northern state of Uttar Pradesh, India. Factors contributing to men's knowledge in the areas of fertility, maternal health and STDs were investigated. Results showed that very few men had basic knowledge in any of these areas. The likelihood of reporting knowledge was associated with a set of determinants that differed in their magnitude and effect across the areas of reproductive health explored. In particular, men's belief about the ability of an individual to prevent pregnancy demonstrated an independent association with men's knowledge. After controlling for factors such as age, parity and educational and economic status, men who believed it not possible to prevent a pregnancy were less likely to know when during the menstrual cycle women would become pregnant and certain facts about STDs, but they were more likely to be able to name two or more symptoms of serious maternal health conditions. Possible explanations for this trend are discussed.

Selection potential based on differential fertility and mortality has been computed for six tribal groups inhabiting different geo-climatic conditions, namely: Sahariya, Mina and Bhil of the State of Rajasthan, north-western India, and Munda, Santal and Lodha of the State of West Bengal, eastern India. Irrespective of the methodology, the total index of selection was found to be highest among Lodhas (0·668), followed by Sahariyas (0·524), Santals (0·462), Bhils (0·386), Mundas (0·353) and Minas (0·334). Incidently, Lodha and Sahariya are two of the seventy-four notified primitive tribal groups of India, and these two study populations show the highest index of total selection, mainly because of a higher embryonic and postnatal mortality.

The relative contribution of the fertility component to the index of total selection is higher than the corresponding mortality component in all tribal groups.

The analysis of postnatal mortality components indicates that childhood mortality constitutes the bulk of postnatal mortality, suggesting that children under 5 years need better health care in these tribal groups.

This paper examines whether infant and child mortality risks among successive siblings are closely correlated, and if so, whether the survival status of the preceding child is an important factor affecting infant and child mortality in Kenya. The data were drawn from the 1988/89 Kenya Demographic and Health Survey. Logistic regression was used as the major method of data analysis. The results show that both infant and child mortality rates are significantly higher among subsequent children whose preceding siblings had died in infancy than for those whose preceding sibling had survived through infancy. The effect of the survival status of the preceding child on infant mortality was statistically strong, even after a large number of control variables were taken into account. However, its effect on child mortality appears to be spurious since it was rendered statistically insignificant when just a few control variables were introduced into the analysis. The results provide empirical evidence that infant and child mortality risks among successive siblings are closely correlated in Kenyan families, and that the effect of the survival status of the preceding child is important in determining infant mortality but not child mortality.

As contribution to a recent debate (James, 1998; Murphy et al., 1997, 1998) the proportion of twins following ovulation induction (OI) or assisted conception (AC) in 1994 in Oxfordshire and West Berkshire was estimated, and by extrapolation the natural twinning rate in England and Wales was judged to have maintained a plateau phase since the 1970s. Similar figures for 1995 and 1996 from the same study, and hence a more stable local estimate, are now provided. The proportions, as before, were estimated from women's responses to a questionnaire within a case-control study, with ascertainment from general practitioners' records or hospital case-notes for non-responders or for those excluded from the study originally. In 1994, 1995 and 1996 the proportion of twins following OI/AC was overall 27% (24%, 30% and 27% respectively). Restriction to the 87% locally resident made no difference. The national crude twinning rate for those years was overall 13·3 per 1000 maternities (12·8, 13·6 and 13·4 respectively).