Birth weight is inversely associated with coronary heart disease in post-menopausal women: findings from the British women's heart and health study

Objectives: (1) To assess the association between birth weight and coronary heart disease (CHD) risk in a cohort of post-menopausal women, (2) to determine the combined effects of birth weight and adult body mass index on CHD, (3) to assess the role of insulin resistance as a mediating factor in the associations. Design: Cross sectional survey. Setting: 23 British towns. Participants: 1394 women aged 60-79 years. Main outcome measures: coronary heart disease (n = 199 cases). Results: Birth weight was inversely associated with CHD: age and survivor status of participant's mother adjusted odds ratio (95% confidence intervals) per 1 standard deviation (0.80 kg) increase in birth weight was 0.84 (0.72 to 0.97). This association strengthened to 0.80 (0.68 to 0.93) with further adjustment for adult body mass index, but there was no evidence of an interaction between birth weight and adult body mass index (p = 0.61). The association was not confounded by childhood or adulthood socioeconomic position or by adult smoking status of the participant. Adjustment for components of the insulin resistance syndrome attenuated the association to 0.87 (0.72 to 1.03). Conclusions: Intrauterine exposures that affect fetal growth also affect future adult CHD risk. The inverse association between birth weight and CHD may in part be mediated via insulin resistance.