Jung, C.Ho, J.Torpy, D.Rogers, A.Doogue, M.Lewis, J.Czajko, R.Inder, W.2012-06-072012-06-072011Journal of Clinical Endocrinology and Metabolism, 2011; 96(5):1533-15400021-972X0021-972Xhttp://hdl.handle.net/2440/71450CONTEXT: There is a paucity of longitudinal data on plasma and urinary cortisol levels during pregnancy using modern assays. Furthermore, conflicting data exist as to the effect of the low-dose oral contraceptive pill (OCP) on cortisol. DESIGN, SUBJECTS, AND MEASUREMENTS: We conducted a prospective longitudinal study on morning plasma cortisol (total and free), corticosteroid-binding globulin (CBG), and 24-h urinary free cortisol (UFC) levels in 20 pregnant women during the first, second, and third trimesters and 2–3 months postpartum compared with 12 subjects on low-dose OCP and 15 nonpregnant subjects not taking the OCP (control group). RESULTS: A progressive rise in total plasma cortisol, CBG, and 24-h UFC was demonstrated during pregnancy, peaking during the third trimester (mean 3-fold rise compared with controls). Plasma free cortisol increased 1.6-fold by the third trimester. In the OCP group, total plasma cortisol and CBG were 2.9- and 2.6-fold elevated, respectively, whereas 24-h UFC and plasma free cortisol were not significantly different from controls. Compared with liquid chromatography-mass spectrometry, a commercial immunoassay underestimated mean total plasma cortisol concentrations by 30% during second and third trimesters and in OCP users and overestimated UFC levels by 30–35% during pregnancy. CONCLUSIONS: Our study demonstrated elevations in total plasma cortisol and CBG concentrations during pregnancy and with low-dose OCP use. Pregnancy was also associated with significant increases in plasma free cortisol and UFC, suggesting that the rise in total plasma cortisol is contributed to by up-regulation of the maternal hypothalamic-pituitary-adrenal axis in addition to elevated CBG.enCopyright © 2011 by The Endocrine SocietyPituitary-Adrenal SystemHypothalamo-Hypophyseal SystemHumansCortisoneHydrocortisoneContraceptives, Oral, HormonalTranscortinBody Mass IndexImmunoassayChromatography, High Pressure LiquidLongitudinal StudiesProspective StudiesPostpartum PeriodPregnancyPregnancy Trimester, ThirdAdultFemaleTandem Mass SpectrometryJournal article002010732310.1210/jc.2010-23950002902106000602-s2.0-7995565829630256Torpy, D. [0000-0002-5069-0981]