Researchers from Washington University in St. Louis and Dartmouth College have uncovered a significant correlation between levels of cortisol in toddlers’ hair—a biomarker indicating long-term stress—and maternal prenatal depression.
Published in the American Journal of Human Biology, the study suggests that conditions experienced by mothers during pregnancy can influence their child’s long-term stress physiology. Theresa Gildner, co-author and assistant professor of biological anthropology at Washington University, emphasized the potential clinical applications of their findings, particularly in understanding how maternal stress impacts offspring development.
Hair cortisol tests were used in the study as a less invasive alternative to blood tests, providing insights into cumulative cortisol exposure over extended periods. Each centimeter of hair corresponds approximately to one month of cortisol accumulation, making it a useful tool for assessing stress levels in infants and toddlers.
The study highlighted the role of the hypothalamic pituitary adrenal (HPA)-axis in managing stress responses. Elevated maternal cortisol levels during pregnancy can cross the placenta, potentially affecting fetal development and leading to adjustments in growth patterns in response to perceived maternal stress. While some adaptations may be beneficial, such as accelerated development in adverse conditions, prolonged exposure to elevated cortisol levels can pose health risks including metabolic diseases, immune dysfunction, and mental health conditions later in life.
Interestingly, the study found that maternal depression during pregnancy, but not postnatal depression, was associated with higher cortisol levels in toddlers’ hair. This underscores the unique impact of prenatal conditions on offspring stress physiology.
Although the study involved a small sample size of 46 mothers and 40 toddlers, aged approximately 15 months, the researchers plan to expand their research with a larger cohort to explore the long-term effects of maternal stress exposure during pregnancy. They aim to investigate how these early-life stress impacts persist into later stages of childhood and adolescence.
The findings suggest the importance of supporting maternal mental health during pregnancy to mitigate potential long-term impacts on children’s health and development.
