Maternal happiness during pregnancy linked to child’s brain development

In a recent study published in the journal Nature Mental Health, researchers explored the relationship between maternal mental health and children’s brain development. Their results contribute to the medical understanding of the importance of the intrauterine environment and suggest that in addition to positive outcomes for the mother, emotional well-being during pregnancy can be an important protective factor for brain development in children.

Study: Maternal positive mental health during pregnancy impacts the hippocampus and functional brain networks in children. Image Credit: Prostock-studio / Shutterstock

Background

Research suggests that depression, anxiety, and stress during pregnancy can have enduring adverse effects on the child’s brain development. Maternal anxiety and depression have been found to affect gray matter density in the medial temporal and prefrontal cortex as well as hippocampal growth.

Maternal health factors can also modify the cortico-limbic system, which helps regulate stress responses and emotional states. These widespread effects have been observed to be more prominent in female children between birth and early childhood. These findings highlight the need to address prenatal mental health to promote brain development in children.

However, emotional well-being is not merely the absence of mental illness but also includes the experience of positive emotions and mental affect. While the effect of positive maternal emotions on parenting behavior, mother-infant bonding, long-term mental health, and child development has been studied, its impacts on brain development have not been explored.

About the study

The study followed a longitudinal prospective birth cohort design to investigate the relationship between maternal well-being and brain development in 7.5-year-old children using magnetic resonance imaging (MRI). This age was chosen because it is a key neurodevelopmental period when significant cognitive processes and brain changes occur.

Participants in the study included pregnant Asian (Malay, Indian, or Chinese) women in their first trimester who were recruited while they antenatal care at an ultrasound scan clinic in Singapore. For the MRI, children were included if they had a gestational age of more than 30 weeks and a birth weight of more than 2 kg to avoid the confounding effects of birth 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 networks. The mental health of the mothers 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 stress, and other topics related to prenatal health and well-being. This information was used to construct an overall socio-environmental adversity factor and scores for four risk domains – personal, interpersonal, socioeconomic, and life stress.

Findings

The sample of participants who underwent the structural MRI included 381 children, of whom 369 also underwent the functional MRI procedure. After controlling for the overall socio-environmental adversity factor and the child’s age during the MRI, researchers found that more positive maternal emotions during the prenatal period were associated with a larger bilateral hippocampal volume in female children but not males. However, maternal positive emotions were not seen to be associated with cortical thickness or volumes of the thalamus, amygdala, lateral ventricles, or basal ganglia.

In terms of functional networks, more maternal positive emotions were associated with higher functional connectivity between the right frontoparietal and visual association networks, salience and thalamo-hippocampal networks, and posterior default mode and attention networks. Notably, these results were significant after controlling for child sex and age as well as postnatal parenting stress and other risk factors. These outcomes were not, however, associated with anxiety or depressive symptoms during pregnancy.

Conclusions

These findings indicate that there may be a neural basis through which positive emotions during pregnancy are transmitted from the mother to her offspring during the early development of the brain. Of the significantly associated outcomes, only the change in the bilateral hippocampi differed between male and female children. This research implies that ensuring mothers’ mental health could lead to sustained benefits for offspring in terms of neural development.

While the study has several strengths and offers novel insights, the authors acknowledged some limitations. While brain development was assessed through neuroimaging, data on maternal mood and well-being were collected through subjective reports and may, therefore, be subject to biases related to recall and social desirability. Self-reports of positive emotions may not be an adequate proxy for psychological well-being, a complex and multifaceted issue. The study participants were all Asian, leading to a lack of generalizability to other populations.

Future studies can build on these findings by including individuals of other races and factoring in positive emotions during other stages (such as during the postnatal 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 children are not just healthy but happy, too.