Parity-related variation in cortisol concentrations in hair during pregnancy

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

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

An antenatal care clinic in southeast Sweden.

390 pregnant women.

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

Hair cortisol concentrations.

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.

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.

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