Talk Therapy for Depression in Pregnancy Is Linked to Differences in Babies' Brains

Babies whose mothers had eight weeks of talk therapy for depression during pregnancy had a smaller right hippocampus, a part of the brain involved in memory and emotion, at about 6 weeks old than babies whose mothers had usual care, according to a follow-up of a US trial published October 16 in Nature Communications. Across all the babies, a smaller hippocampus at 6 weeks went with less fussing and distress at 6 months.

An earlier study found that babies whose mothers had more depression in pregnancy had a larger hippocampus at 2 to 6 weeks old, though infant studies have not all agreed. Some scientists read a larger size that early as a sign of a brain maturing too fast under early stress, which may leave a child more open to mental health problems later. The authors write that their results "are consistent with the possibility that the intervention may attenuate accelerated maturation", meaning the therapy may have slowed that early rush.

Studies like that could only show that a mother's depression and her baby's brain differences turned up together. "By using a randomized clinical trial, we were able to test whether treating depression during pregnancy can actually influence early brain development in infants," said Catherine Demers, an assistant professor of psychiatry at the University of Colorado Anschutz and the study's lead author.

“Our findings suggest that treating mother's depression during pregnancy may help shape a healthier developmental trajectory for the infant brain.”

— Elysia Davis, professor of psychology, University of Denver

The Therapy Was Eight Weekly Sessions About Relationships and Support

The Care Project enrolled 234 pregnant women in the Denver area who scored high on the depression screening their obstetric clinics already gave as part of routine care. About half were on Medicaid.

Half the women were assigned to brief interpersonal psychotherapy, a talk therapy that works on a woman's relationships and the support around her: one getting-started session, then eight weekly one-on-one sessions of 50 minutes. The other half kept their normal obstetric care, with one extra hour with a study clinician about depression in pregnancy, information about local mental health services and regular check-ins. For the new paper, the team scanned 109 of the babies once, at about 6 weeks old, and watched them in a standard lab task at 6 months.

Depression Fell Sharply for the Mothers Who Had Therapy

The researchers estimate that depression affects 20% to 40% of women during pregnancy. In the Care Project, about 37% of the women in each group had major depression at the start. By the end of pregnancy, that had dropped to 6.1% of the women who had the therapy and 26.1% of those on usual care, the team reported in JAMA Psychiatry in 2023. Depression symptoms in the therapy group fell by 47% on a standard checklist, compared with 13% for usual care, and the researchers report that the therapy also benefited birth outcomes, including longer pregnancies.

A year after giving birth, 4.3% of the therapy group had major depression, against 12.9% of the usual-care group, according to a follow-up of 230 of the women published in the Journal of Mood and Anxiety Disorders in December 2025.

The Researchers Say the Long-Term Effects Are Not Yet Known

Only the right side of the hippocampus differed between the two groups; the left side and the amygdala, another emotion-related area, did not differ significantly. The link between a smaller hippocampus and a calmer baby at 6 months was modest. The results held when the researchers accounted for the mothers' medication use, their depression after birth and their health in pregnancy. Because the babies were scanned in their first weeks, the authors say the differences are more likely to trace back to pregnancy than to life after birth.

The authors write that "the long-term developmental significance and biological mechanisms underlying these differences remain untested." The baby measures were an extra question on top of the trial's main goal, which was treating the mothers' depression. Each baby had a single scan, and all the families lived in one US city and spoke English.

The authors describe the therapy as "non-invasive" and "relatively low-cost", and the team says its findings make the case for building mental health care into prenatal visits.