A Longitudinal Study of Plasma and Urinary Cortisol in Pregnancy and Postpartum

• Published in: The journal of clinical endocrinology and metabolism Vol. 96; no. 5; pp. 1533 - 1540
• Main Authors: Jung, Caroline, Ho, Jui T., Torpy, David J., Rogers, Anne, Doogue, Matt, Lewis, John G., Czajko, Raymond J., Inder, Warrick J.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Oxford University Press 01.05.2011; Copyright by The Endocrine Society; Endocrine Society
• Subjects: Adult; Biological and medical sciences; Body Mass Index; Chromatography, High Pressure Liquid; Contraceptives, Oral, Hormonal - adverse effects; Cortisol; Cortisone - blood; Endocrinopathies; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Globulins; Hormones; Humans; Hydrocortisone - blood; Hydrocortisone - urine; Hypothalamic-pituitary-adrenal axis; Hypothalamo-Hypophyseal System - physiology; Hypothalamus; Immunoassay; Liquid chromatography; Longitudinal Studies; Mass spectroscopy; Medical sciences; Oral contraceptives; Pituitary; Pituitary-Adrenal System - physiology; Plasma; Postpartum; Postpartum period; Postpartum Period - blood; Postpartum Period - urine; Pregnancy; Pregnancy Trimester, Third - blood; Prospective Studies; Tandem Mass Spectrometry; Transcortin - metabolism; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Human; Urine; Corticosteroid; Obesity; Nutrition; Steroid hormone; Nutrition disorder; Antiinflammatory agent; Metabolic diseases; Cortisol; Hydrocortisone; Puerperium; Glucocorticoid; Blood plasma; Pregnancy; Follow up study; Adrenal hormone; Female; Woman; Endocrinology; Nutritional status
• ISSN: 0021-972X; 1945-7197; 1945-7197
• DOI: 10.1210/jc.2010-2395

Context: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.