Prenatal Sleep Quality, Neonatal Brain Volume, and Infant Emotion at 6 Months of Age

ABSTRACT Although pregnancy‐related sleep disturbances are known to affect maternal health and fetal development, only recently have studies focused on the impact of maternal sleep quality on fetal brain development and infant social‐emotional outcomes. The present study expands upon this work and examines associations between prenatal sleep, brain regions implicated in emotional regulation and psychopathology (hippocampus and amygdala), and infant negative affect at 6 months. In a sample of 103 pregnant people from the Brain and Early Experience Study, maternal sleep was assessed around 28 weeks of gestation using the Pittsburgh Sleep Quality Index (PSQI). At 2 weeks postpartum, infant brain anatomy was assessed via MRI, and infant negative affect was measured at 6 months using the Infant Behavior Questionnaire. Analyses revealed that poor prenatal sleep quality (global PSQI score) did not significantly predict neonatal hippocampal or amygdala volume. However, exploratory analyses of PSQI subscales found that greater prenatal sleep disturbances were associated with smaller right hippocampal volume in neonates. Mediation analyses indicated that prenatal sleep disturbances were indirectly associated with higher infant negative affect via reduced right hippocampal volume, and this indirect effect was moderated by child sex, such that it was significant among females but not males. These findings highlight the importance of maternal sleep quality in shaping early brain development, particularly in girls, and underscore the long‐term implications for emotional and social development. Promoting optimal sleep during pregnancy may foster healthier emotional outcomes and social functioning in children.