This paper reports the results of a June 1980 survey of 1069 children in Changsha, Hunan Province. The data have been unavailable previously either in Chinese or in English. In general, they suggest that comparisons of single children with children from multiple-child families in China regarding quality of life, intellectual development, and behavioural traits are similar to comparisons conducted in the United States and other western countries. As in many western studies, single children in China appear to have a better quality of life than children with siblings. Regarding intellectual development, single children in China perform better than those with siblings, a finding which is consonant with the family intactness model of Falbo. Single children in Changsha are little different from ones from multiple-child families on various aspects of behaviour, and are more co-operative and less hostile. These findings are the opposite of those of the Shanghai study, the other major analysis of single children in China; the Shanghai survey indicated that single children were not as well-behaved as those with siblings, a finding that caused some concern among Chinese social scientists. To the extent that the findings of the Changsha study, and not those of the Shanghai study, reflect the situation of single children in China, this could mean that the one-child family planning campaign may not be having a negative impact on children's behaviour.

The extent to which it is possible to recognize distinctive patterns of marriage and fertility within sub-groups of the rural population is examined by an analysis of the fertility experience of 294 females who lived in a single village in southern Normandy at some period between 1901 and 1975. Aggregate analysis demonstrates the existence of differential fertility between classes. Examination of circumstantial evidence for individual sub-groups suggests that attitudes towards capital accumulation and inheritance are the major explanatory factors for these differentials.

In the population of 242,633 draftees examined in the Copenhagen area for the period 1956–77, 1143 were extremely overweight. Compared to 2123 controls, selected at random from the remaining draftee population, the obese had a lower educational attainment, even at each level of intelligence test score. Conversely, at each educational level, the obese did not differ from the controls in intelligence test score. When taking into account, by regression analysis, both intelligence test score and parental social class, the chance for the obese of exceeding the educational level of minimum years of schooling followed by elementary trade training increased from 37% to only 52% of that for the controls. The results suggest that obesity, irrespective of social origin, is associated with poor educational attainment which may be responsible for the cognitive deficiency manifested in lower intelligence test scores.

In a WHO-co-ordinated prospective multi-centre study in Agra and Chandigarh (India), Cali (Colombia), Ibadan (Nigeria), Manila (Philippines) and Nottingham (UK), 926 women undergoing elective sterilization for fertility control and 924 controls using other methods of contraception, were examined before the operation and at entry into the study, respectively. Of the initial sample, 81·6% were re-examined at a 6-month follow-up and 77·4% at a 12-month follow-up. At initial examination, the prevalence of clinically significant emotional disorder ranged from 1·6% to 14·6% in four of the six centres; it was higher in Cali (25·5%) and nil in Ibadan. In all centres except Agra, women applying for sterilization had a somewhat higher rate of mental health problems than control subjects at initial examination. At the 6-month follow-up, the prevalence was within the range 1·6–15·4% for the sterilization group and 0–14·5% for the control group in all centres except Cali which continued to have a higher rate. At the 12-month follow-up the prevalence of mental ill-health ranged from 0% in Manila to 29·2% in Chandigarh; if the latter centre were removed, the range would be 0–13·6%. There were no significant differences in the frequency of mental ill-health between sterilization cases and control subjects in any of the centres. Further, there were no significant differences in the prevalence of mental ill-health in relation to the timing of sterilization, i.e. interval, post-partum or post-abortion. Chandigarh was the only centre which showed a consistent increase of the rates of psychological disorder over time; in all other centres the rates showed some fluctuations but no clear tendency either to increase or decrease. The data do not support a notion of a significant impact of sterilization on mental health of women.

The evolution of the inbreeding coefficient estimated by the isonymic method is studied in a rural canton of mid-France, using data divided into 10-year intervals of 6277 marriages recorded in the civil registers between 1870 and 1979. The results show a strong diminution of the values of F from 1930 onwards, probably related to the drop in population due to exodus from rural areas. The evolution of the inbreeding coefficient observed in three large occupational groups (farmers, craftsmen and labourers) shows that after 1930 it was only the farmers who maintained the low positive values of F. The coefficient of genetic relationships by isonymy (Ri) calculated among the principal occupational groups shows their community of origin, which is still perceptible today.

Some initial results from the recently conducted Northern Ireland Fertility Survey are examined with particular reference to the relationship between family size and religious denomination. While the overall average family size of Roman Catholics is still larger than that of non-Catholics, the extent of this differential is now narrowing as a result of the more rapid recent decline in the average size of Catholic families. In addition, there are variations in family size among the main Protestant denominations; a broad regional dimension to the Catholic-non-Catholic differential is also apparent. Although subsequent analyses will document these trends in greater detail, some of the main hypothesized explanatory variables are briefly discussed along with some of the socioeconomic and political implications of these recent trends.

In two groups of people, 98 couples in which the husband was a military serviceman and 63 couples of Jewish ancestry living in Porto Alegre, Brazil, age at marriage, age at time of survey, fifteen anthropometric variables, and hair and eye colour were studied. Proper adjustments of the data were made taking into consideration duration of cohabitation, aging and secular effects, and skewness in the distributions. There are some differences between the two groups in age at marriage, but in both there is a tendency for those currently older to have married later in life. The correlation coefficients between spouses are with very few exceptions positive, with no indication of preferences for opposites. Size and factors related to body build are the most readily detectable agents in the assortative mating occurring in this population, but in the military group relative lengths of leg and trunk, rather than stature itself, are important in conditioning mate choice.

Our ancestors were unique in having the lowest rate of reproduction of any living mammal. This was achieved by the postponement of puberty until well into the second decade of life, a maximal probability of conception of only about 25% per menstrual cycle even when ovulation had commenced, a 4-year birth interval as a result of the contraceptive effects of breast-feeding, and sharply declining fertility during the fourth decade of life, leading to complete sterility at the menopause (Short, 1976, 1983).

As part of a prospective controlled study of the psychosomatic effects of elective tubal sterilization, 138 women were questioned about their menstrual functioning before sterilization, and again 6 months and 12 months post-operatively, using standardized interviewing procedures. Adverse changes, including (subjectively assessed) increased menstrual loss, shorter menstrual cycles and greater use of pads or tampons were reported by sterilized subjects at both of the post-operative interviews. Control subjects reported several comparable effects, although adverse changes overall were reported more commonly by sterilized women than by control subjects. However, many of the reported changes appeared to be related to pre-operative contraceptive methods, although consistent increases in use of pads or tampons were found in women who had pre-operatively used neither the pill nor the IUD.

A retrospective study has been undertaken among 5108 women of the delay in conception after stopping different methods of contraception. Particular attention was paid to the delay that sometimes separates the cessation of contraception and the beginning of intercourse without precautions and to the effect of possible confounding factors.

It was possible to demonstrate a decreased fertility for couples after the pill and, to a lesser degree, after IUD use, but only among those who did not take other precautions (waiting period). For couples observing a waiting period, there is no decrease of fertility following the initial exposure to the risk of conception.

The different prevalence of these confounding factors from one population to another can explain the various results reported of other studies.

The genetic structure and its recent evolution in a small isolated village in the French Pyrenees, Arthez-d'Asson, have been characterized by calculating the probabilities of origin of genes and inbreeding values at every generation since the 17th century.

Arthez-d'Asson appears to be one of the most inbred populations in France, with an inbreeding coefficient of approximately 0·5%. This is due first to genetical and cultural isolation, and secondly to migration out of the village towards towns at the turn of the century. The valley of Ouzom, in which Arthez-d'Asson lies, constitutes a hierarchical population and some cultural and genetical turnover is drawing back to the valley genes which have been absent for some generations.

The paper examines the relationship between infant mortality and a complex measure of socioeconomic status for evidence of diminution. In data on counties in the United States with a minimum of 20 infant deaths over the 5-year period 1971–75, no evidence of a declining relationship between socioeconomic status and infant mortality was found. Both level of community affluence and racial composition of the population exerted direct effects on levels of infant deaths. In addition, both socioeconomic status and racial composition exhibited indirect effects which operated through teenage childbearing. When total infant mortality was subdivided, teenage fertility serves as a mediating variable in the link between socioeconomic status and neonatal mortality, but not for the postneonatal components. Given the nearly equivalent total effect of socioeconomic status on infant mortality, it is concluded that the classic division into neonatal (supposedly a function of biological and genetic agents) and postneonatal (traditionally attributed to social and environmental agents), may be too crude to allow the contemporary effects of the socioenvironmental milieu to be evaluated effectively.

Some hypotheses regarding birth spacing and women's work are outlined. Using British census and survey data it is shown that average second and third birth intervals were shorter in marriages taking place in the 10 years following the Second World War as compared with marriages in the period 1900–29; the intervals increased again, measured on a period basis, in the 1970s. Birth intervals for women married during the 10 years after the war were shorter among those economically active at the 1971 census than among the inactive. Some problems of method are discussed.

Longitudinal studies involving weekly measurement of urinary oestrogen and pregnanediol excretion were performed in 55 post-partum women to identify the patterns of returning fertility. The women kept diaries of breast-feeding episodes, mucus symptoms and times of bleeding; some recorded basal body temperature and acts of intercourse. The study represented a total time of 36 years (7·8 months per woman). The majority of the women were breast-feeding throughout the study. During lactation amenorrhoea, there was complete ovarian quiescence in two-thirds of the subjects and minimal cyclic activity in the others. The first bleeds were associated with anovulatory ovarian activity in 40% of the women, with normal ovulation in 19%, with ovulation but short luteal phases in 25% and with ovulation but deficient luteal phases in 16%. The incidence of normal ovulatory cycles increased with time after delivery and with the number of cycles after delivery and eventually reached 85% even though many women were still breast-feeding at the time. Twenty-two pregnancies occurred, fourteen being unplanned: eight women were fully breast-feeding at the time of conception. Mucus symptoms correlated with the hormone values in approximately 60% of cycles. However, some women had symptoms which were difficult to interpret during their early cycles or potential fertility was not indicated by raised mucus scores or the presence of the peak mucus symptom. These problems together with the resulting confusion appeared to be the major causes for the unplanned pregnancies. Methods for coping with these problems are discussed.

Cross-sectional studies in Australia and the Philippines and a longitudinal prospective study in a selected Australian sample of breast-feeding mothers have shown that basal serum prolactin (PRL) concentrations are elevated during 15–21 months of lactational amenorrhoea.

A predictive model of serum PRL levels and return of cyclic ovarian activity during full breast-feeding, partial breast-feeding and weaning has been developed from the results of breast-feeding behaviour and serum PRL, gonadotrophin and oestradiol measurements in 34 mothers breast-feeding on demand for a mean of 67 weeks.

Breast-feeding patterns influence serum PRL levels. Important factors during full breast-feeding are the age of the baby, the longest interval between feeds at night and total 24-hr suckling time, and following the introduction of supplements, the mean interval between feeds, together with the total 24-hr suckling time and the number of solid supplements per day.

The precise mechanisms whereby breast-feeding regulates cyclic ovarian activity remain unknown. Gonadotrophin secretion appears to be quantitatively normal, but qualitative changes, secondary to altered hypothalamic activity, may be the most important factor. A direct inhibitory effect of PRL on ovarian follicular development and steroidogenesis remains possible.

Ovulation with a normal luteal phase is probable for 30% of breast-feeding mothers before the first menses, but is unlikely before 6 months, provided breast-feeding is frequent day and night.

Measurement of serum PRL is a sensitive index of the return of menstruation and fertility during lactation in the population studied.

Fifty-seven women (mean age = 23·5 years), half of whom used an oral contraceptive, completed Moos' menstrual distress questionnaire at each of the three menstrual phases. In addition they kept menstrual diary cards for 50 days, recording days on which menstrual blood loss occurred. During an intermenstrual phase, they completed: a general information questionnaire with questions on menstrual, socialization and demographic variables; Eysenck's personality inventory; the multidimensional health locus of control scale; the Bern sex role inventory; and a measure of preventive health behaviour. Analyses investigating the effects of pill use and psychological factors on the incidence and intensity of menstrual distress found few significant associations between these measures, especially when symptom changes over the menstrual cycle were the dependent variables. The implications of these results for the aetiology of menstrual distress are discussed.

The analysis based on data collected as a part of the World Fertility Survey programme in four Muslim populations—Bangladesh, Java, Jordan and Pakistan—did not show a consistent pattern in rural–urban differentials in marital fertility. While no significant differential in current fertility by place of current residence is noticeable in Bangladesh and Pakistan, urban women in Jordan showed lower fertility than their rural counterparts. Cumulative fertility, when controlled for duration of marriage, was found to be higher in urban than in rural areas of Bangladesh and Pakistan, but no clear pattern emerged in Jordan. In Java, both current and cumulative fertility were higher in urban than in rural areas; urban women who had spent their childhood and were brought up in the urban environment showed, in most instances, higher fertility than the other residence groups.

Data from the 1971 Census records included in the OPCS Longitudinal Study were used to examine the relationship between geographic mobility and marriage termination and remarriage. Remarried women had high rates of mobility and there seemed to be a clear ‘excess’ of moves made around the time of remarriage, shortly after the end of the first marriage. There was a suggestion too of a peak in movements following widowhood but no indication of excess movement at the time of de jure divorce. The data were not adequate to allow examination of moves made at the the time of separation. Additional data from linked 1971–81 Census information showed that changes of marital status were strongly associated with changes of tenure. Other characteristics of divorced, widowed and remarried women were also examined to see how they might affect their patterns of geographic movement.

Variations in sex ratio with maternal age, paternal age, parity and time have been examined in data on all legitimate births (live and stillbirths) in England and Wales, 1968–77. There were significant linear declines in sex ratio with both increasing parity and increasing paternal age, and a curvilinear relationship with maternal age. These effects were largely independent. Before 1955 it seems likely that sex ratio declined with increase in maternal age. But it seems that between 1955 and 1968 there was an unexplained decline in the sex ratio of births to women aged 20–24 and an increase in that of births to women aged 30–34. There was no significant secular trend in sex ratio during the period 1968–77.