Parity-related variation in cortisol concentrations in hair during pregnancy

Abstract

Objective: To investigate hair cortisol concentrations (HCC) monthly in pregnant women and to explore the effect of parity.

Design: Prospective cohort study from gestational week (GW) 26, at childbirth and postpartum.

Setting: An antenatal care clinic in southeast Sweden.

Sample: 390 pregnant women.

Methods: Cortisol was measured using radioimmunoassay in methanol extracts of ground hair samples.

Main outcome measures: Hair cortisol concentrations.

Results: Both primi- and multiparae exhibited an increase in HCC throughout pregnancy. Primiparae had significantly higher HCC in the latter part of the last trimester compared with multiparae (1 month P = 0.003, 2 months P = 0.038). The use of psychotropic medication in the first trimester correlated to HCC postpartum (P < 0.001). HCC in GW 14-17 was associated with HCC in GW 18-21 (primiparae and multiparae, P < 0.001), GW 22-25 (primiparae P = 0.036, multiparae P = 0.033), and 2 months postpartum (primiparae P = 0.049). HCC in GW 18-21 was associated with GW 22-25 in both primiparae (P < 0.001) and multiparae (P < 0.001) as well as 2 months prior to childbirth among primiparae (<0.037). In general, all estimates of HCC in pregnancy and postpartum showed a significant association between HCC for a specific month and the HCC in the previous month (all P < 0.001), except for the association of HCC among primiparae in GW 22-25 and 3 months prior to childbirth.

Conclusions: Increased cortisol concentrations in hair were observed during pregnancy, which decreased 3 months prior to childbirth in multiparae. The results indicate a quicker suppression of the hypothalamic CRH (corticotropin-releasing hormone) production by placenta CRH in multiparous women.

Tweetable abstract: Multiparae have a quicker suppression of hypothalamic CRH production by placenta CRH during pregnancy compared to primiparae.

Keywords: Cortisol; hair; hypothalamic-pituitary-adrenal pregnancy axis; women.