This Study, the first of a series on consanguinity in the Archbishopric of Toledo from 1900 to 1979, analyses in detail the types of consanguineous mating in a population of considerable size, some 650,000 persons, in central spain. during the period covered, very important transformations occurred in Spanish society. The data relate to 21,464 consanguineous marriages. They were divided into two groups, according to the premarital migration of the couple. Significant differences in the frequencies of the types of consanguineous matings, and their secular evolution, are found for the two groups. The expected trend in inbreeding in the total area shows two different tendencies: constancy till the end of the 1950s, followed by a fast decline during the last two decades.

The cost effectiveness of various modes of family planning service delivery based on the cost per couple-year of protection (CYP) is assessed using 1984 data for 63 projects in ten countries (three each in Africa and Asia, and four in Latin America). More than 4·8 million CYPs were provided through these projects during the year studied. Programmes with the highest volume of services delivered corresponded to lowest average costs: social marketing (2·8 million CYPs) and sterilization projects (960,000 CYPs) cost about $2 per CYP, on average; highest costs were for full service clinics and community-based distribution projects ($13–14 per CYP). Costs of clinics combined with community-based distribution services fell approximately midway between these two extremes.

A survey of men's behaviour and opinions with respect to family planning, undertaken in Dakar in 1986, shows that contrary to popular belief, acceptance of contraception at least for the purpose of spacing births is substantial, even among men from the most conservative backgrounds. Actual use of contraceptives varied considerably across occupations. Among functionaries and students, it ranges between 25 and 49%. Among the working class, prevalence is low, especially within marriage. Uncertainty about the position of Islam regarding fertility control is apparent even among the highly educated and is given as a reason for rejecting use of contraceptives.

In Canadian society the influence of first birth timing on the subsequent birth interval has been eroded over time, as shown by the Canadian Fertility Survey of 1984. The influence of first birth timing is significant for second births among women married during the baby boom period, but not for those married thereafter. Religiosity, marital status, and place of residence are significant factors in second birth timing in Canada.

Using individual birth history data from the Sudan Fertility Survey, 1979, parity-related differences in fertility are demonstrated, as well as differences between socioeconomic groups. Rural women, women with no education and those married to uneducated husbands show rapid parity progression and its cumulative effects on fertility which are consistent over all birth intervals. Urban women, women with some education and those married to educated husbands, however, go rapidly through their second and third birth intervals and then more slowly at higher parities. A limitation of the study was the inability to control fully for the effects of breast-feeding and contraception.

There is evidence for a reduction in high parity births,' starting in the 1970s.

Earlier studies on the seasonality of births indicate that a major peak occurs in August and September and a minor peak in January and February. This study uses the 1984 Canadian Fertility Survey data on reproductive history to examine birth and pregnancy seasonalities, and shows that the ‘worst’ months for births are January and February and the ‘best’ months are March, April and May. There is no systematic pattern in the seasonality of pregnancies, possibly because effective birth control allows couples to plan the timing of births.

The menarcheal age and frequency of menstrual disorders in mothers of dizygotic (DZ) and monozygotic (MZ) twins born in Denmark in 1984 or 1985 were compared with a control sample of mothers of singleton infants born in the same period. Compared to control mothers, mothers of DZ twins had a lower menarcheal age and a lower frequency of menstrual irregularities—menstrual cycles exceeding 5 weeks duration, varying length of menstrual cycles and episodes of menostasia. Mothers of MZ twins had a higher frequency of intermenstrual bleeding compared to mothers of singletons. All results were adjusted for maternal age and parity. The findings are relevant to the interpretation of aetiological factors leading to twin births and support the hypothesis of differences in sex hormone activity of the mothers of DZ twins in comparison with other women.

Using medical records from maternity clinics in the two Norwegian cities Oslo and Bergen, the effect of lactation on infant mortality during the period 1860–1930 is examined, comparing those who were and were not breastfed in a total of about 6900 live born infants. The mortality of children not breast-fed was nearly three times that of those who were breast fed. In a Cox regression analysis the infant's year of birth and the mother's marital status were found to influence mortality in addition to lactation. Children born to unmarried mothers experienced a mortality about twice that of those born to married mothers, both during on-going lactation and in the absence of lactation, up to about 1915. Children born in Oslo had a slightly higher mortality than those born in Bergen.

The duration of lactation was found to have a continuing protective effect on infant survival after weaning—the longer the duration, the lower the mortality after cessation of lactation.

The relationship is examined of child mortality in Ghana with six socioeconomic factors: mother's type of place of residence, education, occupation and work status, and current husband's education and occupation. Using data from the 1979–80 Ghana Fertility Survey, Trussell's marriage duration model was employed to estimate probabilities of dying at exact ages 2 and 5 in different population subgroups. The two education variables (mother's and husband's education) have the largest effect on child mortality, followed by husband's occupation and mother's occupation, in that order. In order to reduce child mortality to tolerable levels, expansion is urgently required of the medical and health services, balanced by an equal development of education, particularly of girls, help being given especially to the rural areas where the majority of the population live.

The influences of household economic condition, maternal education, sex, and nutritional status of children on mortality were examined using multivariate analytical techniques. Weights of around 1700 children aged 2–60 months in five villages of Matlab, Bangladesh, were taken during the first half of 1981. The children were followed for 18 months and their survival was recorded. The severely malnourished children had a risk of death nine times that of their counterparts with better nutritional status. Female children had a higher risk of death than the males. Mother's education and economic condition of household also showed negative relationships with the risk of death, but the effect of mother's education was modified by economic condition and sex of the children.

A life table analysis is made of the duration of breast-feeding and postpartum amenorrhoea in Orissa, India, taking one variable at a time using data from a baseline survey of fertility and mortality (BSFM) conducted on the lines of the World Fertility Survey. Then a multivariate (proportional hazard) analysis showed that socioeconomic factors including residence, caste status and education influence the breast-feeding and post-partum amenorrhoea periods. There was no effect of maternal age on the length of breast-feeding, but mean length of post-partum amenorrhoea varied with age. The durations of breast-feeding and post-partum amen orrhoea are strongly related.