Variation of Human Milk Glucocorticoids over 24 hour Period

Human milk (HM) contains a complex array of hormones, including members of the glucocorticoid family. The predominant glucocorticoids, cortisol and cortisone may influence the growth and behaviour of the breastfed infant. However, little is understood of the factors regulating the levels of these hormones within HM. The aim of the study was to examine HM cortisol and cortisone concentration, measured in samples collected at each feed during a 24 hour period. Twenty three exclusively breastfeeding mothers collected milk, prior to and after each breastfeeding session over 24 hour period at 3.2(1.60) months. HM cortisol and cortisone levels were measured using high pressure liquid chromatography mass spectroscopy. Cortisone was the predominant glucocorticoid (3.40 ng/ml), and cortisol was detected in all samples (1.62 ng/ml). A positive correlation was found between cortisone and cortisol ( r = 0.61, y = 1.93 ± 0.24, p