Depression during pregnancy affects infant brain development

A study published in 2026 in Nature Communications suggests that depression during pregnancy may influence the brain development of infants. Researchers looked at children whose mothers had been part of a clinical trial focused on depression during pregnancy.

Different treatments for maternal depression

Some mothers in the study received brief interpersonal psychotherapy, which aimed to improve relationships and social functioning, leading to reduced depressive symptoms compared to those who received enhanced usual care. This distinction was important for tracking the effects on their babies.

MRI scans of infants’ brains

The study followed 109 babies, and MRI scans of their brains were conducted at about 6 weeks old while they slept naturally. These scans allowed researchers to examine early brain structures and their development.

Smaller hippocampus in some infants

At 6 months, scientists observed the babies' emotional reactions during a standardized exercise. Babies whose mothers received psychotherapy during pregnancy had, on average, a smaller volume of the right hippocampus, a brain region involved in memory and stress response. No significant differences were found for the left hippocampus or the amygdala.

Smaller hippocampus not necessarily worse

The researchers noted that a smaller hippocampus volume does not necessarily indicate poorer brain development. They suggested that prenatal stress might accelerate the maturation of certain brain regions, though this hypothesis requires further confirmation.

Emotional reactivity linked to brain size

A smaller hippocampus volume at 6 weeks was associated with reduced negative emotional reactivity at 6 months, as seen in the babies’ reactions to a small robot that moved and made noise. This indicates a possible link between brain structure and emotional responses.

Study findings not definitive

The study emphasizes that these findings do not guarantee better emotional development from prenatal psychotherapy, as the observed differences may change as the children grow. The researchers call for further studies on larger groups and with longer follow-up periods.