this association. Firstly, poor social circumstances could lead to both lower birth weight and higher mortality risk. Secondly, maternal health, nutritional, and behavioural profiles could influence both birth weight and cardiovascular mortality. Thirdly, intergenerational factors—such as genomic and epigenetic processes that lead to a positive correlation between the birth weights of mothers and their offspring—could influence cardiovascular risk. Adjustment for socioeconomic position and marital status had little influence on the findings in either the current study or the previous investigation of this issue, rendering a simple explanation in terms of socioeconomic confounding unlikely. In the current study we had no data on health status, but in the earlier study adjustment for a wide range of measures of health and health related behaviours reduced only slightly the association between infants’ birth weight and mothers’ cardiovascular mortality. The magnitude of the association in the current study is too great to be generated plausibly by the known associations between birth weight and maternal smoking, alcohol drinking, or anthropometry. The marked similarity between the current findings and those from the previous study—which related to an earlier generation of women living in widely different circumstances—suggests that an important influence is being uncovered by our analyses. Possible intergenerational influences on birth weight and cardiovascular risk therefore merit further investigation.