Maternal plasma and milk free cortisol during the first 3 days of breast-feeding following spontaneous delivery or elective cesarean section.

In a view of the increased clinical interest in the presence of hormones in human milk, the objective of this study was to evaluate maternal plasma and milk cortisol levels in early puerperium and their relationship in breast-feeding in women who underwent elective cesarean section or who delivered vaginally. During the first 3 days of breast-feeding, plasma and milk cortisol levels declined significantly both in women who underwent elective cesarean section and in women who had spontaneous deliveries. Moreover, the breast-feeding procedure did not affect maternal plasma and milk hormonal levels, since no differences between the cortisol levels measured immediately before and after morning daily breast-feeding were detected. Furthermore, a very high positive correlation (p < 0.001) was found between plasma and milk cortisol concentrations. Therefore, maternal plasma cortisol levels can be considered a very reliable measure to predict the hormonal concentration in breast milk.