Associations of early growth and adult adiposity with patterns of salivary cortisol in adulthood

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: The objective of the study was to assess whether prenatal 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 body mass index (BMI) (7 yr); and height, BMI (33 yr), and waist-hip ratio (WHR) (45 yr) were measured in the 1958 British birth cohort. Setting: All study subjects were born in England, Scotland, and Wales in 1 wk in March 1958. Participants: A total of 6,470 participants with salivary cortisol were gathered from 12,069 invitees (54%) at 45 yr. Main Outcome Measures: Two saliva samples on 1 d were collected: 45 min postwaking (t1) and 3 h later (t2). Three cortisol outcomes were measured: t1 level, area-under-curve, 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 3 nmol/liter, 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 7-yr 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 area-under-curve. Conclusions: Smaller head circumference, shorter stature, lower BMI, and WHR are associated with higher cortisol levels.