How maternal distress affects neurologic development in children

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The first few years of a child’s life are at a stage of great brain plasticity and neurodevelopment, and form the foundation for their future cognitive, social, and emotional skills. This period, extending from the fetal stage up to about 2 years of age, is heavily influenced both by the environment and the behavior of the child’s caregiver. In particular, maternal psychological distress—including stress, anxiety, and depression—during both the prenatal and postpartum periods is a massive risk factor for delay in the child’s developmental process.

Despite the established link between a mother’s mental health and child’s development, researchers have struggled to pinpoint the best time for targeted intervention. Is it more critical to address distress during pregnancy or during the first postpartum year? Answering this question has proved difficult owing to the bidirectional relationship at play: just as a mother’s psychological distress can negatively affect the child’s development, a child’s health issues or developmental delays can similarly increase maternal distress. While previous studies have revealed associations, a causal relationship has not been confirmed so far.

To shed light on this issue, a research team led by Junior Associate Professor Kenta Matsumura from the University of Toyama (now a Professor at the Aomori University of Health and Welfare) in Japan, conducted a rigorous large-scale investigation. As reported in their latest study, published JAMA Network Open on October 31, 2025, the team used advanced statistical modeling to estimate the independent causal effects of maternal psychological distress at specific time points on neurodevelopmental outcomes in young children. The paper was co-authored by Dr. Tomomi Tanaka, Dr. Akiko Tsuchida, and Dr. Hidekuni Inadera from the University of Toyama.

The researchers gathered data from the Japan Environment and Children’s Study, an ongoing, nationwide birth cohort study. The final analysis included a large dataset of 82,418 mother–child pairs, ensuring a statistically robust and representative sample of Japanese mothers. The team measured maternal psychological distress at two key time points: during mid- to late pregnancy and 1 year after childbirth. The primary outcome considered was neuropsychiatric developmental delay, assessed every 6 months from 1.5 to 3 years of age.

Using a marginal structural modeling approach based on causal inference to account for time-varying and bidirectional confounding, the researchers successfully quantified the independent causal effect of distress at each period. A key finding was that maternal psychological distress experienced at 1 year postpartum was more strongly associated with neurodevelopmental delay in toddlers, compared to the distress experienced during mid/late pregnancy. This finding was consistent across all five developmental areas, and the effects were found to be additive—experiencing distress at both pregnancy and postpartum further amplified the risk of delays. “The results from our study clearly highlight the need to support maternal mental health at all times from pregnancy through 1 year postpartum,” remarks Dr. Matsumura.

Overall, the study underscores the critical importance of effective screening and intervention for postpartum mental health while still recognizing the necessity of prenatal support. “In designing public health, maternal and child health, and child-rearing support policies, these insights will be essential to support evidence-based decision-making,” concludes Dr. Matsumura.

Hopefully, further studies in this area will provide more actionable knowledge, leading to a lower incidence of neurodevelopmental delays and maternal stress alike.

Source: News Release
University of Toyama
December 8, 2025