Higher prenatal anxiety predicts lower neonatal hair cortisol.

Background: Prenatal glucocorticoids are one of the most widely proposed prenatal programming mechanisms, yet few studies exist that measure fetal cortisol via neonatal hair. Neonatal hair provides a window into the fetal experience and represents cortisol accumulation in the third trimester of pregnancy. In the current study, we test the links between two types of anxiety over the course of gestation (pregnancy-related anxiety and general anxiety) with neonatal hair cortisol.

Method: Pregnant individuals (N = 107) and their neonates (59.8% female) participated in the current study. Prenatal pregnancy-related anxiety and general anxiety were measured using the Pregnancy Related Anxiety Scale (PRAS) and the State-Trait Anxiety Inventory (STAI), in each trimester of pregnancy. Hierarchical linear modeling was used to model the intercept and slope of each type of anxiety over gestation. Neonatal hair samples were collected shortly after birth (Median = 1.17, IQR = 0.75-2.00).

Results: Both higher pregnancy-related anxiety and general anxiety at the beginning of pregnancy and a flatter decline of pregnancy-related anxiety over gestation were associated with lower neonatal hair cortisol. After inclusion of gestational age at birth and parity as covariates, pregnancy-related anxiety (intercept: β = -0.614, p =.012; slope: β = -0.681, p =.006), but not general anxiety (intercept: β = -0.389, p =.114; slope: β = -0.302, p =.217) remained a significant predictor. Further, when both general and pregnancy-related anxiety were entered into the same model, only pregnancy-related anxiety (intercept and slope) were significant predictors of neonatal hair cortisol, indicating an association with pregnancy-related anxiety above and beyond general anxiety.

Conclusion: Cortisol plays a central role in maturation of fetal organ systems, and at the end of gestation, higher cortisol has beneficial effects such as promoting fetal lung maturation. Further, lower maternal cortisol is linked to less optimal cognitive development and altered brain development. As maternal higher anxiety in early pregnancy and a flatter decrease over time are both associated with lower neonatal hair cortisol, maternal pregnancy-related anxiety could be a target of future intervention efforts.