Urinary cortisol and depression in early pregnancy: role of adiposity and race

Background: Depression before and during pregnancy is associated with adverse birth outcomes including low birth weight and preterm birth. Abnormal maternal cortisol has been hypothesized as one mediator between depression and adverse birth outcomes. The relationship between cortisol and depression in pregnancy is exhibited most strongly in the African American population, and most studies have focused either on circulating or placental levels of cortisol. The utility of urinary cortisol in early pregnancy related to depression and adiposity has not been investigated. Methods: Twenty-five pregnant African American women identified by the Edinburgh Depression Scale as having depression were investigated and matched by body mass index (BMI), age, race, and infant birth weight centile to non-depressed subjects. Maternal urine and plasma cortisol in early pregnancy were quantified and investigated in relation to depression and adiposity. Results: Morning urine cortisol levels tracked positively with plasma cortisol (r(2) = 0.25, p < 0.001). However, no differences were observed in either urinary or plasma cortisol between depressed and non-depressed pregnant women. Plasma cortisol was significantly negatively associated with several measures of maternal adiposity including percent body fat (r(2) = -0.10, p < 0.05), however this relationship was present only in the non-depressed women. In a post-hoc analysis, non-depressed non-obese women were found to have significantly higher cortisol levels compared to women with depression, obesity or both (p < 0.05). Conclusions: Depressed pregnant women and non-depressed obese pregnant women evidence atypical cortisol levels compared to non-depressed non-obese pregnant women. Plasma cortisol in early pregnancy is negatively associated with measures of maternal adiposity. Atypical low circulating maternal cortisol among depressed (lean and obese) and non-depressed obese pregnant African American women may indicate hypothalamic-pituitary axis dysfunction in early pregnancy.