In a recent study published in the journal Dr Nature is mental health, researchers explored the relationship between maternal mental health and children’s brain development. Their findings contribute to medical understanding of the importance of the intrauterine environment and suggest that in addition to positive outcomes for mothers, emotional well-being during pregnancy may be an important protective factor for brain development in children.
Study: Positive maternal mental health during pregnancy affects the hippocampus and brain functional networks of infants. Image credit: Prostock-studio / Shutterstock
Research suggests that depression, anxiety and stress during pregnancy can have lasting adverse effects on the baby’s brain development. Maternal anxiety and depression have been shown to affect gray matter density in medial temporal and prefrontal cortex as well as hippocampal growth.
Maternal health factors can also modulate the cortico-limbic system, which helps regulate stress responses and emotional states. These widespread effects have been shown to be more prominent in female children between birth and infancy. These findings highlight the need to address prenatal mental health for brain development in children.
However, mental well-being includes not only the absence of mental illness but also the experience of positive emotions and emotional affect. Although the effects of positive maternal emotions on parenting behavior, mother-child bonding, long-term mental health, and child development have been studied, its effects on brain development have not been explored.
About the study
The study followed a prospective longitudinal birth cohort design to investigate the relationship between maternal health and brain development in children aged 7.5 years using magnetic resonance imaging (MRI). This age was chosen because it is a key neurodevelopmental period when significant cognitive processes and brain changes occur.
Study participants included pregnant Asian (Malay, Indian or Chinese) women in their first trimester who were recruited during antenatal care at an ultrasound scan clinic in Singapore. For MRI, infants were included if their gestational age was greater than 30 weeks and their birth weight was greater than 2 kg to avoid confounding effects of congenital complications.
The authors hypothesized that positive emotions during pregnancy would be associated with significant differences in brain structures, such as the amygdala and hippocampus, as well as functional networks, such as the default mode and visual network. Maternal mental health was assessed using the Beck Depression Inventory, the Edinburgh Postnatal Depression Scale and the State-Trait Anxiety Inventory.
Additionally, the survey included questions on socioeconomic status, relationships with friends and family, life stressors, and other topics related to prenatal health and well-being. This information was used to create an overall socio-environmental adversity factor and scores for four risk domains – personal, interpersonal, socioeconomic and life stress.
The sample of participants who underwent structural MRI included 381 children, of whom 369 underwent a functional MRI procedure. After controlling for overall socio-environmental adversity factors and infant age at the time of MRI, the researchers found that more positive maternal emotions during the prenatal period were associated with a larger bilateral hippocampal volume in female infants but not males. However, maternal positive emotions were not found to be associated with cortical thickness or volume of the thalamus, amygdala, lateral ventricle, or basal ganglia.
In terms of functional networks, more maternal positive emotions were associated with higher functional connectivity between right frontoparietal and visual association networks, salience and thalamo-hippocampal networks, and posterior default mode and attention networks. Notably, these results remained significant after controlling for infant gender and age, as well as postpartum parenting stress and other risk factors. These findings, however, were not associated with anxiety or depressive symptoms during pregnancy.
These findings suggest that there may be a neural basis by which positive emotions during pregnancy are transmitted from the mother to her offspring during early brain development. Among the significantly associated outcomes, only change in bilateral hippocampi differed between male and female children. This research suggests that ensuring maternal mental health can lead to long-lasting benefits for offspring in terms of neurodevelopment.
Although the study has several strengths and offers novel insights, the authors appreciate some limitations. While brain development was assessed by neuroimaging, data on maternal mood and well-being were collected by subjective report and, therefore, may be subject to biases related to recall and social desirability. Self-report of positive emotions may not be an adequate proxy for psychological well-being, a complex and multifaceted issue. The study participants were all Asian, thereby lacking generalizability to other populations.
Future studies could build on these findings by including individuals of other races and factors in positive emotions at other stages (such as the postpartum period). This work adds to a growing body of literature showing the transgenerational nature of mental health outcomes and the importance of ensuring that mothers and babies are not only healthy but happy.
- Positive maternal mental health during pregnancy affects the hippocampus and brain functional networks of infants. Qui, A., Shen, C., López-Vicente, M., Szekely, E., Chong, Y., White, T., Wazana, A. Nature is mental health (2024). DOI: 10.1038/s44220-024-00202-8, https://www.nature.com/articles/s44220-024-00202-8