WOMEN experience unique changes in grey matter volume, white matter tracts, and functional neural network organisation after a second pregnancy, a 2026 prospective cohort study has found using brain MRIs.
Neurostructural changes carried implications for mother-infant attachment and peripartum depression.
This follows established findings that a first pregnancy changes women’s brain structure and resting-state brain activity.
Maternal Mental Health
Structural changes across both first and second pregnancies were associated with maternal mental health.
They were more strongly associated with postpartum depression and psychological distress in the postpartum period in first-time mothers, and during pregnancy in second-time mothers.
Dr Elseline Hoekzema, head of Pregnancy Brain Lab at Amsterdam University Medical Center, Amsterdam, the Netherlands, said: “With studies like these we hope to increase our understanding of the neurobiology of these disorders of maternal mental health.
“This can render insights into the development of these disorders and factors that are involved in this, which could potentially contribute to an earlier recognition of these disorders.
“In the Pregnancy Brain Lab, we are currently also setting up clinical studies in women suffering from postpartum depression and mother-infant bonding disorders in order to examine the brain in these clinical groups in detail.”
Brain Structure in Pregnancy
Hoekzema and her team performed a prospective pre-conception cohort study that analysed MRI data before pregnancy and in the early and late postpartum periods.
MRI scans were analysed from 40 women undergoing a first pregnancy, 30 women undergoing a second pregnancy, and 40 nulliparous women.
Researchers were able to classify whether a woman had undergone a first or second pregnancy based solely on brain changes shown in the MRI data.
They found widespread decreases in cortical brain volume across a second pregnancy compared to control women, similar to those seen in a first pregnancy.
Both first and second pregnancies strongly impacted the introspective default mode network and the frontoparietal networks and one of its major white matter trats, the superior longitudinal fasciculus, pointing to enhanced plasticity.
Differences Between First and Second Pregnancies
These changes were more prominent in a first pregnancy, suggesting it is primarily adapted in first-time mothers, and then fine-tuned during subsequent pregnancy.
Differences in patterns of neural change and the degree to which different networks are affected were observed between first and second pregnancies.
It follows that subsequent pregnancies are associated with distinct neural transformations.
Areas specifically affected after a second pregnancy were mainly located in, for example, the somatomotor and dorsal attention networks.
These networks are involved with responsiveness to external stimuli, goal-oriented attention, and task demands.
Researchers have speculated that said changes prepare a woman for the increased demands associated with caring for multiple children at the same time.
Challenges
Due to ethical constraints, researchers were not allowed to acquire MRI scans during pregnancy. Hence, the exact timing of the pregnancy-induced brain changes could not be found.
Further, the study cannot comment on the cellular processes behind such changes. Classification analyses also require larger cohorts.
Reference
Straathof M et al. The effects of a second pregnancy on women’s brain structure and function. Nat Commun. 2026;DOI:10.1038/s41467-026-69370-8.
Featured image: Gorodenkoff on Adobe Stock
