This study analysed factors associated with unintended pregnancy among adolescent and young adult women in Santiago, Chile. Three variations of a behavioural model were developed. Logistic regression showed that the effect of sex education on unintended pregnancy works through the use of contraception. Other significant effects were found for variables reflecting socioeconomic status and a woman's acceptance of her sexuality. The results also suggested that labelling affects measurement of ‘unintended’ pregnancy.

The duration of postpartum amenorrhoea was studied in a danish sample of 361 women. The median duration of amenorrhoea was 17 weeks. The 25th and 75th percentiles were 10 and 30 weeks, respectively. A significant correlation was found between the duration of postpartum amenorrhoea and of breast-feeding. However, loctation for more than 9 months did not extend the duration of amenorrhoea. Menstruation before weaning occurred in 57% of the women, and 43% terminated breast-feeding before the first menstruation. Four weeks after weaning menstruation had returned in 79% and by 8 weeks after in 93% of the mothers. At 6 months postpartum, frequency of breast-feeding, and of night-time feeding were determinants of amenorrhoea.

It has been suggested that average genetic similarity, as assessed by blood genetic markers, could influence mate choice in humans. In the present study, average genetic similarity was assessed in 183 couples submitting to paternity determinations in relation to six blood group systems and three HLA loci. Couples in which the putative father was excluded were compared with those in which such exclusion did not occur, and real couples were compared to random pairs. The differences were all statistically non-significant. Possible reasons for the different results found in the previous sample and in the present study are considered.

This study investigates the effect of both total and unsupplemented breast-feeding in conjunction with birth interval on early childhood mortality, using longitudinal data from Matlab, Bangladesh. A discrete hazard model approach shows that it is not the duration of total breast-feeding but the duration of unsupplemented breast-feeding which increases child survival. Unsupplemented breast-feeding appears as such a crucial determinant of early childhood mortality that its effect could not be substantially attenuated even when important demographic and socioeconomic factors were controlled. Each of the covariates—supplementation, previous birth interval and onset of a subsequent conception—has an independent influence on early childhood mortality.

The genetic structure of Sicily was analysed through the distribution of surnames of 758,793 users registered in the Italian Telephone Company, corresponding to 371 communes of the island. Estimates of the coefficient of consanguinity due to random isonymy, of Fisher's a, an indicator of abundance of surnames, and of Karlin–McGregor's v, an indicator of immigration rates, were obtained for each commune. Four different estimates of genetic distance between all possible pairs of communes within each province were also obtained, and their relationship with geographic distance was studied. The logarithmic transformation of Lasker's coefficient of relationship showed correlations with the log of geographic distance which range between −0·78 and −0·40; the strongest, for the province of Catania, was attributed to the presence of Mount Etna, and the weakest, for Palermo, to the high population density of this province.

The accuracy of responses to a question on the frequency of sexual intercourse in the 4-week period prior to an interview is expected to be low. This paper examines the reliability of an alternative question: ‘How many days since you last had sexual intercourse?’. This was a part of a larger longitudinal study of fertility dynamics in Matlab, Bangladesh. The response pairs of 61 women who were asked the same question by an interviewer and on the next day by a supervisor, were analysed. Refusals were more common among older women and among women who gave a response at the extremes of the distribution for the other interview. Of the pairs of two responses, 78% had a difference of 3 days or less. Further study and use of the question on days since last intercourse is recommended.

A new analysis of a randomised double-blind trial confirms the fact that vitamin–mineral supplementation has a statistically significant effect on non-verbal IQ as measured by the WISC-R test. Further studies may show if this effect is large enough to be of practical importance.

Assortative mating for 22 anthropometric and body composition characteristics and social indicators was studied in a Spanish sample of 114 married couples. Significant spousal similarity was found for occupation, educational level and number of siblings. Sex–age adjusted spouse correlations were significant for stature, ileospinal height, total arm length, and biacromial breadth. Spouse correlations were not altered after allowance for socioeconomic effects. When couples were grouped according to marriage duration, differences in mate correlations for fatness were detected, suggesting a cohabitational effect on spouse resemblance.

Data from the 1991 Belize Family Health Survey show differentials in the use of maternal and child health services between ethnic groups (Creole, Mestizo, Maya/Ketchi and Garifuna). Multivariate analysis is used to explore whether such differentials can truly be attributed to ethnicity or to other characteristics that distinguish the ethnic groups. Health services considered are: family planning, place of delivery (hospital/other), postpartum and newborn check-ups after a birth, and immunisations for children. The language usually spoken in the household is found to be important for interpreting ethnic differentials. Mayan-speaking Maya/Ketchis are significantly less likely to use family planning services or to give birth in a hospital. Spanish-speakers (Mestizos and Maya/Ketchis) are less likely to use newborn and postpartum check-ups, after controlling for other characteristics. There are no ethnic differentials for immunisations. Programmatic implications of these results are discussed.

In April 1990, the prices of five brands of contraceptives in the Bangladesh social marketing project were increased, by an average of 60%. The impact on condom sales was immediate and severe, with sales for the following 12 months dropping by 46% from the average during the preceding 12 months. The effect on oral contraceptive sales was less dramatic: average sales in the year following the increases dropped slightly despite a previously established pattern of rapidly rising sales. There appears no reasonable combination of events other than the price increase itself to explain most of the difference.

Relationships were examined between sibling variables, perceptions of learning environments and aspirations for Australian adolescents from family contexts defined conjointly by human and social capital. Generally, the findings using a regression approach indicated that sibling variables continued to have significant and often complex associations with adolescents' aspirations after taking into account relationships between perceptions of learning environments and aspirations. Also, relationships between sibling variables, perceptions of learning environments and aspirations, varied for adolescents from the different family contexts.

Data from the 1988 Tanzania census were used to examine child mortality in three regions populated with Burundi refugees. Logistic and least squares analyses show that for both Tanzanian nationals and refugees low levels of maternal education are associated with high child mortality levels. Children born to mothers who are housewives are associated with low levels of mortality compared to those born to employed mothers, though the results were not statistically significant for the refugees. Maternal demographic status, computed from age and parity, has a strong effect on child survival. Unexpectedly, child mortality was lower where the water source was a well outside the village. Tanzanian mothers who are at highest risk of childbearing are roughly 6·4 times more likely to have a child death than those at lowest risk; the corresponding figure for the refugees is 36·8. This emphasises the need to intensify family planning programmes in these regions.

Postpartum sexual abstinence may be a major determinant of fertility and of maternal and child health in sub-Saharan Africa. This study examines the relationship between ethnicity and abstinence using data from the 1988 Ghana Demographic and Health Survey. There is considerable diversity in the length of abstinence although only for one ethnic group, the Mole-Dagbani and other Ghanaians, is abstinence, both actual and ideal, very long. Respondents in most ethnic groups believe their abstinence to be adequate. A key motivation for abstinence is the unwillingness to have sexual intercourse with nursing mothers. Education, urbanisation, changes in marriage patterns and religious traditions are major factors shaping the ethnic differentials in abstinence. In comparison to breast-feeding, abstinence appears to have relatively little impact on the length of the birth interval and, for Ghana, has relatively few implications for fertility and child health.

This paper explores the importance of gender differences in the impact of tropical diseases on women. Malaria and schistosomiasis are used as examples but most of the observations also apply to other diseases endemic to developing countries. The distinction between sex and gender is discussed and evidence of sex and gender differences in the determinants and consequences of malaria and schistosomiasis, particularly their economic, social and personal dimensions, is reviewed. Issues on which research and intervention studies are needed are identified.

The relationship between chronic parasitic loads and psychopathology is examined. Research suggests that: (1) psychiatric disorders are more prevalent in less developed countries where parasitic loads are more endemic; (2) individual patients with parasitic loads are more likely to exhibit mental status changes; (3) there is an improvement in the mental status of a subset of psychiatric patients following treatment for parasites. Inasmuch as the prevalence of parasitic content is underestimated in both more developed and less developed countries, an awareness of this relationship should increase understanding of the needs of infected individuals, and be taken into consideration when evaluating psychiatric patients.

This paper examines the effects of a child's place of birth, mother's education, region of residence and rural and urban residence on infant mortality in Nigeria between 1965 and 1979, using data from the 1981/82 Nigeria Fertility Survey. Infant mortality rates declined in all regions between 1965 and 1979. Children born in modern health facilities, irrespective of their mothers' place of residence, experienced significantly lower rates of infant mortality than those born elsewhere. Logistic regression analysis showed that all other variables tested were also significant, although some to a lesser degree. Efforts to reduce infant mortality in Nigeria should include policies that rectify rural and urban differentials in the distribution of health facilities and encourage their use.

The degree of isolation was assessed in two contrasting regions in Northern Palencia, Spain, one mountainous with small villages in the valleys (Pernia), the other lower and more open (Ojeda), with corresponding differences in economy. Using data from the parish and diocesan records, the frequencies of consanguineous marriages were calculated from the dispensation data, and the evolution of inbreeding compared. The more isolated region shows a greater degree of inbreeding, though not as high as in some other parts of Spain. Both regions show a decline in inbreeding with time, though in neither did the results indicate that geographic isolation was very outstanding. The most frequent types of consanguineous unions occur between second cousins.

The daily activities observed in a Colombian village community of contemporary hunting and gathering people were analysed with respect to their time structure. Short term cycles of about 2 hours could be detected in both individual and common behavioural patterns. These behaviour cycles of individual group members appear to have been synchronised by social interaction. From temporal variations of individual activities a common ultradian time frame emerged.

Results of a survey of some urban areas in the Pretoria–Witwatersrand–Vereenining region show differential impacts of proximate and socioeconomic factors on the fertility of urban blacks and whites. Timing of starting and ending of childbearing and the reproductive behaviour of women who have never been married account for the major differences in fertility levels. White women confine their childbearing career to the 20–39 age range, while black women utilise the entire 15–49 age range. The fertility level is quite high among black women who have never been married (in contrast to never married white women). With the exception of breast-feeding, racial patterns in other proximate determinants of fertility do not suggest the observed racial differentials in fertility.

A survey of 673 consecutive Papua New Guinea parturients carried out at the Port Moresby General Hospital between May and June 1990 showed that socioeconomic and educational factors played a part in predicting perinatal death. Mothers who have previously experienced a perinatal death are more likely to experience a second one.