Psychological distress and salivary cortisol covary within persons during pregnancy.

The mechanisms whereby maternal stress during pregnancy exerts organizational effects on fetal development require elaboration. The aim of this study was to assess the plausibility of cortisol as a biological link between maternal psychological distress during pregnancy and fetal development. Previous research has resulted in equivocal findings for between-persons differences in stress and cortisol. Ecological momentary assessment was used to simultaneously assess mood and cortisol 5 times daily for 3 days in 83 women (gestational ages 6-37 weeks). Results from multilevel analysis indicated a robust within-person association between negative mood and cortisol. For each 1.0% increase in negative mood there was a corresponding 1.9% increase in cortisol. This association was unaffected by advancing gestational age. The results suggest that cortisol is a plausible biological mechanism for transducing the effects of maternal psychological distress during pregnancy to fetal development.