Study finds prenatal sleep quality affects newborn brain structure and emotional health

Findings suggest prenatal sleep quality as a key factor influencing infant brain and emotional outcomes.

Study: Association between prenatal maternal sleep quality, neonatal uncinate fasciculus white matter, and infant negative emotionality. Image Credit: ambrozinio/Shutterstock.com

In a recent study published in the eBioMedicine, a group of researchers investigated how prenatal maternal sleep quality affects neonatal brain white matter development and subsequent infant negative emotionality.

Background 

Sleep disturbances frequently increase during pregnancy and are linked with poorer maternal mental and physical health. However, the intergenerational impact of prenatal sleep disruptions remains underexplored.

The Developmental Origins of Health and Disease (DOHaD) model suggests that early life periods, including prenatal phases, significantly influence health across the lifespan.

Prior studies have shown that inadequate prenatal maternal sleep affects birth outcomes, such as preterm birth and low birth weight, and may influence offspring socioemotional development, including heightened negative emotionality, a risk factor for later mental health challenges. Further research is needed to clarify these neurobiological pathways.

About the study 

At three points during pregnancy (16, 29, and 35 weeks), pregnant participants self-reported sleep quality. Around five weeks post-birth, neonatal white matter microstructure in their infants was assessed via magnetic resonance imaging (MRI), conducted while the infants were naturally asleep.

This timing allowed researchers to focus on prenatal influences while minimizing postnatal environmental factors. Infant negative emotionality was then evaluated at six months through laboratory observations and maternal reports.

The study included 116 mother-infant pairs recruited from the broader Care Project, which investigates how interpersonal therapy affects prenatal maternal depression and child health outcomes. Only participants not receiving therapy were included.

The cohort was socioeconomically and racially diverse, reflecting Denver’s demographics. To support accessibility, researchers offered flexible scheduling, daycare assistance, and online options.

Prenatal sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI), which assesses various aspects of sleep on a scale where higher scores indicate poorer quality. Sixty-five percent of participants reported poor sleep early in pregnancy, rising to 70.7% later.

Infant negative emotionality was evaluated through maternal reports and a robot-based behavioral task measuring distress.

MRI scans assessed the white matter in key fronto-limbic tracts relevant to emotional development, specifically the uncinate fasciculus and cingulum bundle, with thorough quality controls to ensure data reliability.

Statistical models examined sleep trajectories and links to white matter and emotionality, adjusting for prenatal stress, anxiety, and depression. The study explored neonatal white matter as a potential mediator between prenatal maternal sleep quality and infant negative emotionality, with additional sensitivity and sex-based analyses to clarify findings. 

Study results 

The progression of prenatal maternal sleep quality was best modeled by a quadratic growth curve, indicating that sleep disturbances typically worsened as pregnancy advanced. Statistical model fit indices confirmed this quadratic relationship, revealing a significant worsening of sleep problems later in gestation.

Analyzing the impact of these sleep quality trajectories on neonatal brain structure, poorer maternal sleep quality throughout gestation was associated with increased fractional anisotropy (FA) (a measure of the directionality of water diffusion in brain tissue) in the uncinate fasciculus of neonates.

This relationship held even after controlling for potential confounding factors, such as income-to-needs ratio. Further analyses explored whether specific diffusion metrics, such as radial diffusivity (RD) or axial diffusivity (AD), were linked to prenatal maternal sleep quality, finding an association with RD but not AD in the bilateral uncinate fasciculus.

Conversely, prenatal maternal sleep quality was not significantly associated with FA in the neonatal cingulum, suggesting a more targeted impact on the uncinate fasciculus rather than broader fronto-limbic circuitry.

Additional analyses accounted for prenatal stressors, maternal anxiety, and depression, finding that associations between poor maternal sleep quality and neonatal uncinate fasciculus FA persisted despite these factors.

Sensitivity analyses, including the exclusion of cases with prenatal substance use or preterm birth, showed consistent patterns, supporting these findings.

Analyses of control tracts, specifically the corticothalamic-parietal and corpus callosum tracts, revealed no significant associations between maternal sleep quality and FA, underscoring that observed associations were specific to the uncinate fasciculus and not general to white matter structure.

Given the significant relationship between prenatal maternal sleep quality and uncinate FA, mediation analyses were conducted to examine whether neonatal uncinate FA mediated the relationship between prenatal sleep disturbances and subsequent infant negative emotionality.

Results indicated that poorer prenatal maternal sleep indirectly predicted greater negative emotionality in infants through increased bilateral uncinate FA. Additional analyses focused on the timing of prenatal sleep problems (early, mid, and late pregnancy) did not yield a distinct timing-based pattern.

Exploring potential sex differences, regression analyses tested whether the infant’s sex moderated the association between maternal sleep quality and neonatal white matter FA in the uncinate fasciculus and cingulum.

Findings showed no moderating effect of sex, suggesting that associations between prenatal maternal sleep quality and neonatal fronto-limbic white matter are not influenced by the infant’s sex.

Conclusions 

To summarize, prenatal maternal sleep quality impacts neonatal fronto-limbic development and predicts higher infant negative emotionality, a risk factor for later mental health issues.

Increased sleep disturbances across pregnancy correlate with higher FA in the neonatal uncinate fasciculus, which is associated with emotional processing. This early maturation effect, specific to the uncinate, may shorten developmental plasticity, leading to increased susceptibility to psychopathology.

Importantly, associations with FA persist beyond prenatal stress or mental health influences, underscoring prenatal sleep’s unique impact on infant brain development. These findings highlight the need for prenatal sleep interventions to promote healthier child neurodevelopment.