title: Latent trait cortisol (LTC) during pregnancy: Composition, continuity, change, and concomitants.
abstract: Individual differences in the activity of the hypothalamic pituitary adrenal (HPA) axis are often operationalized using summary measures of cortisol that are taken to represent stable individual differences. Here we extend our understanding of a novel latent variable approach to latent trait cortisol (LTC) as a measure of trait-like HPA axis function during pregnancy. Pregnant women (n=380) prospectively collected 8 diurnal saliva samples (4 samples/day, 2 days) within each trimester. Saliva was assayed for cortisol. Confirmatory factor analyses were used to fit LTC models to early morning and daytime cortisol. For individual trimester data, only the daytime LTC models had adequate fit. These daytime LTC models were strongly correlated between trimesters and stable over pregnancy. Daytime LTC was unrelated to the cortisol awakening response and the daytime slope but strongly correlated with the area under the curve from ground. The findings support the validity of LTC as a measure of cortisol during pregnancy and suggest that it is not affected by pregnancy-related changes in HPA axis function.
authors: Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, Calgary, AB, Canada; Institute for Interdisciplinary Salivary Bioscience Research, Arizona State University, Tempe, AZ, USA. Electronic address: ggiesbre@ucalgary.ca.
authors: Gerald F
authors: GF
authors: Giesbrecht
authors: Institute for Interdisciplinary Salivary Bioscience Research, Arizona State University, Tempe, AZ, USA; T. Denny Sanford School of Social and Family Dynamics, Arizona State University, Tempe, AZ, USA.
authors: Crystal I
authors: CI
authors: Bryce
authors: Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Faculty of Nursing, University of Calgary, Calgary, AB, Canada.
authors: Nicole
authors: N
authors: Letourneau
authors: Institute for Interdisciplinary Salivary Bioscience Research, Arizona State University, Tempe, AZ, USA; The Johns Hopkins University School of Nursing, Baltimore, MD, USA; The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA; The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors: Douglas A
authors: DA
authors: Granger
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007206:Individuality; D010913:Pituitary-Adrenal System / Q000502:physiology*; D011247:Pregnancy; D012463:Saliva / Q000737:chemistry; D055815:Young Adult
chemical_list: D006854:Hydrocortisone
keywords: Area under the curve; Cortisol awakening response; Daytime slope; Latent trait cortisol; Pregnancy; Stability