Women's elevated anxiety, depression and stress during pregnancy altered key features of the foetal brain, which subsequently decreased their offspring's cognitive development at 18 months, according to a study.

These changes also increased internalising and dysregulation behaviours revealed in the study published in JAMA Network Open. The findings further suggest that persistent psychological distress after the baby is born may influence the parent-child interaction and infant self-regulation.

The study is the first to shed light on an important link between altered in-utero foetal brain development and the long-term cognitive development consequences for foetuses exposed to high levels of toxic stress during pregnancy, said researchers from the Children's National Hospital in Washington, US.

"By identifying the pregnant women with elevated levels of psychological distress, clinicians could recognise those babies who are at risk for later neurodevelopmental impairment and might benefit from early, targeted interventions," said Catherine Limperopoulos, chief and director of the Developing Brain Institute at Children's National.

For the study, the team followed a cohort of 97 pregnant women and their babies. While in the womb, the researchers observed changes in the sulcal depth and left hippocampal volume, which could explain the neurodevelopmental issues seen after birth.

Once they grow into toddlers, these children may experience persistent social-emotional problems and have difficulty establishing positive relationships with others, including their mothers. To further confirm this, future studies with a larger sample size that reflect more regions and populations are needed, the researchers said.

Regardless of their socioeconomic status, about one of every four pregnant women suffers from stress-related symptoms, the most common pregnancy complication. The relationship between altered foetal brain development, prenatal maternal psychological distress and long-term neurodevelopmental outcomes remain unknown. Studying in utero foetal brain development poses challenges due to foetal and maternal movements, imaging technology, signal-to-noise ratio issues and changes in brain growth.