The Relation Between Prenatal Stress and Infant Negative Emotionality: Buffering Effects of Maternal Predictability

Prenatal development represents a period of heightened biological sensitivity, during which maternal stress physiology may shape emerging regulatory systems in the fetus. Stress exposure during pregnancy has been associated with later emotional and behavioral vulnerability, yet the mechanisms linking prenatal biology to postnatal socioemotional outcomes remain incompletely understood. A central question concerns whether early caregiving processes can buffer or amplify these prenatal influences.

In this MRI-funded dissertation project, Dr. Özlü Aran (University of Denver) investigated whether trajectories of placental corticotropin-releasing hormone (CRH)—a stress-responsive hormone that rises markedly across gestation—predict infant emotional responding at six months of age. Accelerated increases in placental CRH have been implicated in later risk for preterm birth, making it a biologically meaningful marker of prenatal stress exposure. The study modeled within-person changes in placental CRH across pregnancy and examined whether steeper hormonal increases were associated with greater infant negative emotionality.

Infants completed a structured laboratory assessment involving exposure to a novel, mildly stressful stimulus – an encounter with a dancing robot while their parents were out of sight. Observers coded facial affect, vocal distress, behavioral reactivity, and approach behaviors toward the robot. In parallel, mother–infant free play interactions were videotaped and analyzed using a fine-grained coding system designed to capture maternal predictability. Rather than relying exclusively on global sensitivity ratings, the study employed entropy-based modeling to quantify the moment-to-moment predictability of maternal auditory, visual, and tactile signals—an innovative approach reflecting emerging work on environmental regularity in early development.

Results yielded a nuanced pattern. Accelerated placental CRH trajectories were not directly associated with heightened infant negative emotionality or startle in response to the robot. However, infants exposed to more rapid hormonal increases demonstrated greater likelihood of approaching and touching the novel stimulus, suggesting that prenatal stress biology may relate to patterns of engagement rather than simple distress reactivity. Maternal predictability, although theoretically positioned as a potential buffer, was not significantly associated with reduced negative emotionality nor did it moderate associations between prenatal hormone exposure and infant outcomes in this sample.

While not all hypothesized buffering effects were observed, the study advances a biologically informed, relational model of early development. By integrating gestational stress physiology with micro-level analyses of caregiving behavior, the project refines understanding of how prenatal and postnatal processes intersect. Supported by MRI, this work underscores both the promise and complexity of identifying actionable caregiving targets—such as environmental predictability—for early prevention and intervention efforts aimed at supporting socioemotional development.