This study examines the frequency of consanguineous marriage and the coefficient of inbreeding in the United Arab Emirates (UAE). The study was conducted in Al Ain and Dubai cities between October 1994 and March 1995. A sample of 2033 married UAE females aged 15 years and over participated. The degree of consanguinity between each female and her spouse, and the degree of consanguinity between their parents were recorded. The rate of consanguinity in the present generation was high (50·5%) with a coefficient of inbreeding of 0·0222. The commonest type of consanguineous marriage was between first cousins (26·2%). Double first cousin marriages were common (3·5%) compared to other populations. The consanguinity rate in the UAE has increased from 39% to 50·5% in one generation. The level of consanguinity was higher in Al Ain (54·2%) than in Dubai (40%).

The data from the Demographic and Health Survey conducted in Ghana in 1988 are used to identify determinants of immunisation uptake for children under 5 years. The logistic binomial analysis shows that socioeconomic factors are significant, especially women's education and region, and that the type of prenatal care received by the mother is also important. There is a strong familial correlation of vaccination behaviours, and there is also clustering of data within enumeration areas.

This paper reports the preliminary findings of an analysis of the Moray House (verbal IQ) results of a base sample of 4383 Orkney children due to be tested in the schools at age 11±1½ years in 1947–75. Girls enjoy a 3·63% premium relative to phenotypically equivalent boys at test age. Relationships within the sample, which includes some members of the parental generation, are known. The trait is found to be X-linked, with nine phenotypes in the boys, and lyonization is involved.

Botswana is one of the sub-Saharan countries where actual fertility has declined. This study examines the fertility preferences of both men and women and shows that fertility intentions have a significant influence on future fertility behaviour. Fertility preferences are relatively low and there is no significant difference between those of men and women. Men's preference for sons influences desired family size and eventual fertility. For women as well as men, child survival is an important factor. Women's income is also influential.

This paper proposes a new method of measuring excess risk of child mortality in cross-sectional surveys, which is applied to DHS I data for Burundi, Uganda and Zimbabwe. The expected child mortality experience is estimated for each mother on the basis of child's age, mother's age at child's birth and her parity, and compared with her observed experience. Mothers who exceed their expected child mortality experience and also had more than one child die are considered to have excess child mortality. Zimbabwe had the greatest concentration of child deaths as measured by a simple ratio of mothers to deaths, but when observed experience was compared with expected it had less than half as many excess deaths as Uganda and Burundi. In all three countries mother's education had a strong negative association with the risk of excess child mortality, and in Zimbabwe and Burundi there were significant regional differences.

Birth interval is a major determinant of rates of fertility, and is also a measure of parental investment in a child. In this paper the length of the birth interval in a traditional African population is analysed by sex of children. Birth intervals after the birth of a boy were significantly longer than after the birth of a girl, indicating higher parental investment in boys. However, in women of high parity, this differential disappeared. Birth intervals for women with no son were shorter than for those with at least one son. All these results are compatible with an evolutionary analysis of reproductive decision-making. First born sons have particularly high reproductive success, daughters have average reproductive success and late born sons have low reproductive success. The birth interval follows a similar trend, suggesting that longer birth intervals represent higher maternal investment in children of high reproductive potential.

This paper describes the matrimonial and reproductive behaviour of Italians who migrated to Belgium after the Second World War. Migrants were either already married, or later became married, to other Italians. Among the children of migrants, men equally chose Italian or Belgian wives but women tended to prefer Italian partners. Italian-Belgian marriages were more frequent among the better educated groups. Family size is smaller among migrants marrying after migration and in heterogamous marriages. Significant differences in birth intervals are found when marriage occurred before or after migration, between generations, and between homogamous and heterogamous marriages.

Marriage patterns of California's eighteenth and nineteenth century Spanish-Mexican families are analysed using data from genealogies and mission records. A shortage of women among the military based colonists led to an unusual marriage pattern with a large age differential between husbands and wives. The average age at marriage was 18·4 years for women and 28·4 years for men. Spatial mobility was high for both sexes, particularly for men. More husbands than wives were born in Mexico. The Monterey presidial district of central California was the birthplace of a disproportionate number of husbands and the southern California districts were a source of wives. The transition between a founding population predominantly composed of Mexican immigrants and a population of native-born Californians occurred at the beginning of the nineteenth century.

The cost effectiveness of several modes of family planning service delivery based on the cost per couple-year of protection (CYP), including commodity costs, is assessed for 1991–92 using programme and project data from fourteen developing countries (five in Africa, four in Asia, three in Latin America and two in the Middle East). More than 100 million CYP were provided through these family planning services during the 12 months studied. Sterilisation services provided both the highest volume (over 60% of total) and the lowest cost per CYP ($1.85). Social marketing programmes (CSM), delivering almost 9 million CYPs, had the next lowest cost per CYP on average ($2.14). Clinic-based services excluding sterilisation had an average cost of $6.10. The highest costs were for community-based distribution projects (0·7 million CYPs), which averaged $9.93, and clinic-based services with a community-based distribution component (almost 6 million CYPs), at a cost of $14.00 per CYP. Based on a weighted average, costs were lowest in the Middle East ($3.37 per CYP for all modes of delivery combined) and highest in Africa ($11.20).

Protein energy malnutrition is a major health problem in India and it affects the growth and development of young children. This study investigated the impact of hygiene, housing and sociodemographic variables on acute malnutrition in children aged 5–7, living in urban and rural areas. Ordinal logistic regression analysis showed that the overall prevalence of severe malnutrition was 8·2%. Older age, male sex, mother's poor education, lower family income, higher birth order of the child, use of dung or fire wood as fuel and defecation within the premises were significantly associated with malnutrition. Appropriate intervention programmes should be formulated to educate and support these families.

It has been suggested that parish-based reconstitution studies may underestimate the true age at marriage because they do not normally include data for emigrants who may be expected to behave differently from individuals who remain in their natal parishes. This study uses data from C18-19th parish registers of north-west Germany to estimate the difference in age at marriage between leavers and stayers. The difference is not significant for males; although that for females is significant, it is small and the consequence of failing to include migrants is likely to be negligible for most studies. However, it is shown that there is also an independent effect on age at marriage that is due to the woman's natal social (economic) status; historical demographic studies that ignore this dimension may risk confounding two different effects.

Family planning practices were reported by 491 married women, aged 15-49, who applied to the Family Planning Centre in Isparta, Turkey. Eighty-four percent of the women used contraception, the IUD being used most frequently. Almost half of the women married before age 18 years.

A weighted total of 630 pupils aged 14–15 in Glasgow schools, about evenly divided between pupils of South Asian and non-Asian (overwhelmingly British) background, were measured for height and weight and compared with previous results for a similar Glasgow sample aged 30–40. Among 14–15-year-olds, British Asians were not so short compared with non-Asians as among 30–40-year-olds, especially females. Among 30–40-year-old Glasgow Asians only 7% were born in the UK, while among 14–15-year-old Glasgow Asians 86% were so born, indicating that they are the children of migrants. Generational differences in these comparisons cannot be due to positive selection of the migrant generation for height, and are attributed to improved environment, including nutrition and public health measures. This suggests the possibility of corresponding improvements in coronary and diabetic risk.

According to official census returns from Roman Egypt (first to third centuries CE) preserved on papyrus, 23·5% of all documented marriages in the Arsinoites district in the Fayum (n=102) were between brothers and sisters. In the second century CE, the rates were 37% in the city of Arsinoe and 18·9% in the surrounding villages. Documented pedigrees suggest a minimum mean level of inbreeding equivalent to a coefficient of inbreeding of 0·0975 in second century CE Arsinoe. Undocumented sources of inbreeding and an estimate based on the frequency of close-kin unions (corrected downwards to 30% for Arsinoe) indicate a mean coefficient of inbreeding of F=0·15-0·20 in Arsinoe and of F=0·10-0·15 in the villages at the end of the second century CE. These values are several times as high as any other documented levels of inbreeding. A schematic estimate of inbreeding depression in the offspring of full sibling couples indicates that fertility in these families had to be 20-50% above average to attain reproduction at replacement level. In the absence of information on the amount of genetic load in this population, this estimate may be too high

Trends in multiple birth rates are thought to have been substantially affected by subfertility treatments in the last 25 years, but there are few quantitative assessments of this. This paper examines trends in twin and higher multiple birth rates separately in Scotland, England and Wales and compares their course with corresponding multiple birth rates in the Oxford Record Linkage Study area, where the proportions following subfertility treatment are documented. National data on prescriptions for subfertility treatments reinforce the view that they have had a major effect on the trends, and currently perhaps 60% of triplet and higher order births and 15% of twins follow their use in Britain.

The study investigated whether homosexual men are, on average, born a shorter time after their next-older siblings than are heterosexual men. Because of mixed evidence that birth intervals are longer after a male child, the sex of the next-older sibling was included as a control variable. The probands were 220 heterosexual and 183 homosexual men with at least one older sibling examined in Southern Ontario in 1994–95. These completed a self-administered, anonymous questionnaire concerning their family background and other biodemographic information. The results showed that birth interval was negatively correlated with sibship size, positively correlated with maternal age, and uncorrelated with paternal age. They also confirmed that birth intervals are longer after a male than after a female child. The mean birth intervals preceding heterosexual and homosexual males, however, were virtually identical, indicating that the association of short birth intervals with decreased sex hormone levels in cord blood is unrelated to the development of sexual orientation.

The tenth Annual Workshop of the Biosocial Society will be held on Friday 2 May 1997 at University College Stockton, University Boulevard, Thonaby-on-Tees.