Context: Early growth and obesity are associated with adult chronic disease. A suspected mediator is the hypothalamic-pituitary-adrenal axis and cortisol regulation. Our prior hypothesis was that cortisol levels are affected by anthropometry at several life stages.

Objective. To assess whether pre and postnatal growth and adiposity are associated with adult cortisol levels, and whether early growth and adiposity are related to later cortisol through adult body size.

Design: Weight, head circumference (birth), height and BMI (7y); height, BMI (33y) and WHR (45y) measured in the 1958 British birth cohort.

Setting: All born in England, Scotland and Wales, in one week in March, 1958.

Participants: 6470 with salivary cortisol from 12,069 invitees (54%) at 45y.

Main outcome measures: Two saliva samples on one day: 45mins post-waking (t1) and 3 h later (t2). Three cortisol outcomes: t1 level, area-under-curve (AUC), and abnormal t1-t2 pattern.

Results: WHR was associated with all cortisol measures: among men over the WHR range 0.81-1.05, t1 cortisol decreased by approximately 3nmols/l, and the risk of an abnormal t1-t2 pattern increased by 77%; for women, over the WHR range 0.69-0.93, the risk of an abnormal t1-t2 pattern increased by 74%. For childhood measures, among males, increasing 7y-BMI was associated with decreased t1 cortisol and increased risk of an abnormal t1-t2 pattern. Poorer prenatal growth in women, and postnatal growth in both sexes, was associated with increasing AUC.

Conclusions: Smaller head circumference, shorter stature, lower BMI and WHR are associated with higher cortisol levels.