Objective To ascertain whether maternal twinning influences the previously described association between the birthweight of singleton mothers and their infants. Design and subjects The association between the birthweight of singleton parents and their offspring and that between twin parents and their offspring was compared using data from the 23‐year‐old sample of the 1958 British national birth cohort. The numbers available for full comparison were 1027 female and 611 male singleton cohort members, and 26 female and 17 male twin cohort members and their first singleton livebirths. Results Of the mothers who had been twins, half had been of low birthweight, and overall their mean weight was 700 g less than that of their singleton counterparts. Nevertheless, the mean birthweight of babies of twin mothers was 133 g, and of twin fathers 94 g, greater than of babies of corresponding singletons. For female, but not male, parents this difference persisted after adjustment for confounding variables. Conclusions We suggest two possible reasons for the difference between the weight of babies of twin and singleton mothers. Firstly, the growth of twins becomes retarded late in pregnancy, possibly after a period critical in determining long‐term reproductive effects. Secondly, the twin survivors were of higher birthweight than the original twin cohort, whilst the singleton survivors were more representative of all singleton births, thus introducing a possible bias.

OBJECTIVES: Twelve countries were compared with respect to occupational class differences in ischemic heart disease mortality in order to identify factors that are associated with smaller or larger mortality differences. METHODS: Data on mortality by occupational class among men aged 30 to 64 years were obtained from national longitudinal or cross-sectional studies for the 1980s. A common occupational class scheme was applied to most countries. Potential effects of the main data problems were evaluated quantitatively. RESULTS: A north-south contrast existed within Europe. In England and Wales, Ireland, and Nordic countries, manual classes had higher mortality rates than nonmanual classes. In France, Switzerland, and Mediterranean countries, manual classes had mortality rates as low as, or lower than, those among nonmanual classes. Compared with Northern Europe, mortality differences in the United States were smaller (among men aged 30-44 years) or about as large (among men aged 45-64 years). CONCLUSIONS: The results underline the highly variable nature of socioeconomic inequalities in ischemic heart disease mortality. These inequalities appear to be highly sensitive to social gradients in behavioral risk factors. These risk factor gradients are determined by cultural as well as socioeconomic developments.

Investigations on intergenerational effects on birthweight have been carried out using the data of the 1958 British National Birthday Trust Fund cohort and its follow-up to 23 years, the National Child Development Study (NCDS-4), which included information on all births to cohort members by that age. This report is directed particularly at ascertaining the independent effect of parental gestational age on babies' birthweight. The two main findings are a direct association between parental and offspring birthweight (significant for both mothers and fathers after allowing for confounding factors), but an inverse association with parental gestational age (significant only for the mothers). It is postulated that at least part of this effect is mediated through the association between maternal fetal growth rate and their babies' birthweight; the faster the rate the shorter the gestational age for a given birthweight. It was not possible to ascertain what part genetic factors played in this relationship. Larger and more informative intergenerational studies are needed to further knowledge on this question.

The present account is of data available from the 1958 British national birth cohort and its follow-up to the age of 23 years. It shows an increase in adult height between the cohort members and their parents, amounting to an average 1.2 +/- 0.11 (SEM) cm between the daughters and their mothers and 3.0 +/- 0.12 cm between the sons and their fathers. Factors in early life which contributed jointly to a significant increase in adult height included, as well as sex and parental height, birthweight and maternal pre-pregnant weight, while increasing gestational age had a negative effect. Overall these factors accounted for 71% of the variance of the cohort members' height. Measuring the intergenerational difference between individual pairs of sons and father and daughters and mothers allows to some extent for social and genetic influences. This showed that the size of the difference was increased by increasing intrauterine growth rate, and falling paternal social class. These findings demonstrate again the lifelong influence on offspring of circumstances pertaining at their birth and explain why it may take more than one generation to overcome the effects of childhood disadvantage.