This study surveys 100 married and 100 unmarried primiparous mothers, attending the National Maternity Hospital, Dublin, with regard to their contraceptive practice, their planning of their pregnancy and the timing of their first antenatal visit. Nineteen per cent of the married women, but 64% of the unmarried women, had never used any contraceptive method. The contraceptive pill was the most popular method for both groups, but while three in five of the married women had at some time used the pill, only a little more than one in five of the unmarried women had ever used it. One quarter of the women who had used contraception reported that their pregnancy was the result of a failure in their contraceptive method. Eighty-nine per cent of the single group and 20% of the married had not planned their pregnancy. None of the married women, but almost a quarter of the single, delayed their first antenatal visit until after they were 20 weeks pregnant.

Who are the men and women who are childless in their mid-30s? Life history data for a British cohort born in 1946 show that age at marriage and marital breakdown were clearly associated with childlessness. Women who were only children were more likely to be childless than those with siblings. Further, early menarcheal age, being highly qualified and having a high status occupation were indirectly related to childlessness. For men, particularly amongst those who had experienced a broken marriage, it was the most ambitious, the highly educated and those in professional occupations who were relatively more likely to be childless.

The demand for additional children is influenced by the presence of sons within a family. This study is based on cross-sectional data of 9416 currently married women under age 50 from a Pakistan national survey in 1979–80. The analysis suggests that having at least one son in the family influences the demand for additional children. Urban and rural comparisons indicated a higher preference for sons in urban areas. Unless the socioeconomic milieu changes, son preference is likely to remain strong in Pakistan.

Using Bongaarts' model, the relative importance of the proximate determinants of fertility is explored in five populations on the US–Mexico border. For the groups closest to natural fertility (the two Mexican groups), lactation, use of contraception, and marriage all were moderately important in terms of their direct effect on fertility. For the group with lowest fertility (Anglo-American), contraceptive use was an important factor inhibiting fertility; marriage was important but not nearly as important as contraceptive use. For the two US Mexican-American groups, contraceptive use was an important intermediate variable, not as important as for Anglo-Americans, but more important than it was for the two populations in Mexico. The proportion married was a moderately important factor for the Mexican-American groups. For these five populations the principal differences in fertility rates result from substantial differences in the use of effective contraception. Bongaarts' model proved very useful as an analytical framework in this study.

Lifetime reproductive histories of a 1984–85 nationally representative sample of 870 women aged 25–59 years provided data to describe the evolution of fertility, contraception, breast-feeding, and natural fecundability in Costa Rica between 1960 and 1984. The contraceptive prevalence rate increased from 23% in 1965 to 58% in 1975 and 66% in 1984. Duration of breast-feeding was stable during the 1960s, decreased in the early 1970s, and increased after about 1976. Fecundability among women who did not practise contraception was lower than expected and declined between 1960 and 1975, probably because of selection effects. Despite a high consistency between estimations from the reproductive histories and other sources of data, some suggestion of omissions of short periods of contraceptive use in the distant past was detected. The survey may have reduced recall errors by using a calendar that summarizes major life events together. The analysis demonstrated the feasibility and usefulness of asking for lifetime reproductive histories in fertility surveys in developing countries.

Indirect techniques are applied to estimate the current level of fertility and mortality among Kuwaiti nationals in Kuwait during 1980–85. The various methods discussed provide estimates in the vicinity of 45 per thousand for birth rate and 8 per thousand for death rate. While child spacing by birth order in Kuwait is about 2 years, the proportion of childlessness is very low (1%). As a consequence of lower mortality and stable high fertility, the Kuwaiti population remains young.

In birth certificate data for Massachusetts resident births from 1978 to 1982, 12–27% of births purportedly under 31 weeks of gestation were probably misclassified, i.e. had birthweight ≥2500g. Correcting for maldistribution of births removed 34% and 23%, respectively, of black and white births with reported gestational ages <36 weeks but with implausible weights. Percentages of unknown and incomplete reports of last menstrual period were also significantly higher for blacks. After adjustment, preterm black infants weighed less than whites at each gestational age. The proportion of infants <2500g born at term (≥37 weeks gestation) was higher (although not significantly) among blacks. These findings are consistent with hypotheses that low socioeconomic status negatively affects the rate of intrauterine growth.

As part of an ongoing study on young adult psychological and social development, data were obtained through parental reports on the present residences and educational and occupational attainments of 718 present or former residents of Hawaii (average age 31 years). These subjects, as well as their parents, had been tested between 1972 and 1976 on measures of cognitive abilities and personality. The extent of emigration to the mainland in this middle to upper-middle class sample was over 40%. On average, former Hawaii residents now living on the US mainland were of higher intelligence and educational background than their counterparts still living in Hawaii. Differences were also found for number of children, crossethnic marriages, and occupational attainment (males only). In addition, parents of US mainland residents scored significantly higher on measures of cognitive abilities and education than parents of current Hawaii residents.

Evidence has accumulated to suggest that the mean IQs of Orientals in the United States and in the countries of the Pacific Basin are higher than those of Whites (Caucasoids) in the United States and Britain. This paper presents evidence from IQ tests on 4858 6-year-old Chinese children in Hong Kong. On the Coloured Progressive Matrices these children obtained a mean IQ of 116. Samples from Australia, Czechoslovakia, Germany, Romania, the UK and the US obtain IQs in the range 95–102. It is suggested that these results pose difficulties for the environmentalist explanations commonly advanced to explain the low mean IQs obtained by some ethnic minorities in the United States.

The seasonality of births in the period 1871–1977 is studied in a rural north-western Spanish population. Based on a total sample of 11,695 birth registrations, temporal variation is analysed. For siblings, according to family reconstitution, the total family size, the legitimacy of the child, and birth order are considered. A coefficient of birth month dispersion is defined and estimated for each family. Intra-family variation is related to inter-family coefficients in order to determine whether the local seasonal pattern of births may be partly explained by family characteristics.

As the participants in the 1958 National Child Development Study cohort enter adulthood most of the social factors associated with onset of asthma are no longer relevant, but many of the biological factors continue to be important. There is a continuing association at age 23 between eczema, hayfever and similar allergic reactions and continuing asthma, while the earlier associated social factors including non-manual occupations, home ownership, and lack of crowding within the home or sharing of the bedroom with others in the household cease to have significant effects. Smoking patterns in this age group diverge sharply from what might be expected in those with a serious respiratory affliction: significantly more asthmatics smoke than would be expected at random.

The physical, achievement, and personality characteristics of Chinese schoolchildren are evaluated. The results of two surveys of Chinese schoolchildren, conducted in Beijing and Jilin Province, are presented. In the Beijing sample, the differences between only children and others were small but statistically significant, with the only children having higher scores in achievement and physical size. In the Jilin Province sample, the differences between only children and others were also small but significant. These differences were found entirely in physical characteristics, with only children being smaller, perhaps because the only children in the Jilin sample were much younger than the non-only children. Analyses of the combined sample of Beijing and Jilin schoolchildren indicated that the only-child advantages in achievement were found among children from urban families, not rural peasant families. While significant differences in height and weight were found in all three samples, none of the results indicated a significant difference in the proportion of body fat. None of the analyses indicated that only children had undesirable personalities, as judged by teachers and mothers.