Reference ranges for cortisol and α-amylase in mother and newborn saliva samples at different perinatal and postnatal periods

This paper describes a reliable analytical method based on Ultra High-Performance Liquid Chromatography coupled to tandem mass spectrometry to determine cortisol in saliva samples from healthy mothers (n = 87) and newborns (n = 65) at different time points: (i) 38 weeks of gestation, (ii) in the immediate postnatal period (48 h) after a term delivery and, (iii) 3 months after delivery. The procedure is characterized by a simple sample treatment employing a sample volume of 25 mu L. In addition to this, salivary alpha-amylase was determined using a commercial kit. We have proposed potential reference ranges in saliva for cortisol (0.7-35 nmol L-1) and alpha-amylase (2-500 U mL(-1)) in mothers, and for cortisol (0.1-56 nmol L-1) and alpha-amylase (0.1-500 U mL(-1)) in newborn infants. In addition, statistical differences between the two sensitive population groups (mothers and newborns) at the perinatal and postnatal periods were studied. A lower concentration for maternal cortisol was found at 38 weeks of gestation than at 48 h (p = 0.048) or 3 months after delivery (p = 0.021). Similar results were found for the alpha-amylase determinations. Hence, higher concentrations than could be expected from a chronic stress marker were found at 3 months after delivery than at 38 weeks of gestation (p < 0.001) or 48 h after delivery (p < 0.001). We conclude that this analytical method could be applied to further clinical research on perinatal and postnatal stress, such as threatened preterm labor and/or parenting stress, respectively. (C) 2016 Elsevier B.V. All rights reserved.