Abstract

Objective: To study whether the effect of size at birth on the risk of ischaemic heart disease (IHD) death is modified by social circumstances in childhood or in adulthood.

Design: A cohort study. Data on circumstances at birth were retrieved from archived obstetric records, social characteristics in adulthood and mortality follow-up through routine registers.

Participants: 6159 men and 5663 women who were born in Uppsala University Hospital, Sweden (the Uppsala Birth Cohort) during 1915–1929, were singleton births with more than 30 weeks of gestational age and were alive in 1961. Follow-up time 1961–2002 (from age 31–46 to 73–88 years).

Main outcome measure: Death from IHD. Multivariate Cox regression with age as the time scale, controlling for year of birth and stratified by gender.

Results: The risk of IHD death was lower among men and women with higher weight for gestational age. Lower social class in adulthood was associated with a higher risk of IHD death. The effect of size at birth on IHD mortality did not appear to be modified by social class at birth but was only present in men of higher social class in adulthood (hazard ratio per 1 SD weight for gestational age 0.84, 95% CI 0.75 to 0.93).

Conclusions: Weight for gestational age was inversely associated with the risk of IHD death in men and women; this effect was present in men of non-manual adult social class only but did not appear to be modified by adult social class in women or by social class at birth in either men or women.