Serum and saliva cortisol relations in adolescents during pregnancy and the early postpartum period

The purpose of this investigation was to examine: (1) relations between serum and saliva cortisol in adolescents in pregnancy and early postpartum and (2) short-term consistency of serum and saliva cortisol across three samples, 20 minutes apart, as well as the long-term consistency from pregnancy to early postpartum. Pregnant adolescents (n = 40), ages 14 to 19years, were enrolled in this study. Subjects were seen at 20 weeks gestation or earlier (T1), 34-36 weeks gestation (T2), and 2-3 weeks postpartum (T3). Blood samples were drawn at T1 and T3, at 0, 20, and 40 minutes. Saliva samples were collected across the same 40-minute period at T1, T2, and T3. Spearman rho (r_s) correlation coefficients between serum and saliva ranged from 0.72 to 0.77 (T1), and 0.42 to 0.60 (T3) (p ≤ 0.05). Short-term consistency between serum cortisol samples was 0.86-0.97 at T1 and 0.60-0.82 at T3. Short-term consistency for saliva cortisol samples was 0.70-0.96 at T1, 0.91-0.95 at T2, and 0.64-0.89 at T3. Long-term consistency (T1 to T3) for serum and saliva cortisol was low. Individual differences as well as dramatic changes in the endocrine environment in pregnancy and the early postpartum period may explain the more moderate serum-saliva correlations in the postportum period.