Along with her team, Dr. Suzanne King, a researcher at the Douglas Research Centre and Professor Emerita at McGill University’s Department of Psychiatry, has just published an article investigating how the prenatal maternal stress can effect the human reproductive system long-term. The article, entitled “Prenatal maternal stress is associated with alterations in the structural integrity of the hypothalamic–pituitary–gonadal axis 20 years later: Project Ice Storm,” was published on May 21, 2026 in Human Reproduction.
KEY TAKEAWAYS
The study shows that prenatal maternal stress (PNMS), from a natural disaster, has long-lasting effects on the human reproductive system. Exposure during pregnancy was linked to structural changes in the hypothalamic–pituitary–gonadal (HPG) axis in offspring nearly 20 years later. Higher stress levels were associated with altered hypothalamic and pituitary volumes, disrupted typical sex differences, and changes in gonadal structure (e.g., smaller testes in men and more ovarian follicles in women). Overall, PNMS appears to influence sexual differentiation and reproductive development in a sex-specific way.
WHY THIS MATTERS
Understanding how stress during pregnancy shapes long-term biological outcomes in the offspring is critical for public health and developmental science. The HPG axis controls puberty, fertility, and reproductive health. If prenatal stress can alter its development, it may contribute to fertility issues, altered puberty timing, and broader health differences later in life. This study provides rare human evidence—using a quasi-experimental natural disaster—that prenatal stress can have enduring physiological consequences beyond maternal personality characteristics.
WHAT THEY DID
Researchers used data from Project Ice Storm, a longitudinal study of individuals whose mothers experienced varying levels of stress during the 1998 Quebec ice storm. Prenatal stress was measured both objectively (e.g., days without electricity, financial hardship) and subjectively (psychological distress). At age 18.5, participants (39 exposed, 31 controls) underwent MRI scans to measure hypothalamus, pituitary, and gonadal structures. Hormone levels (testosterone and estradiol) and ovarian follicle counts were also assessed. Statistical analyses examined relationships between PNMS and structural outcomes, and tested whether PNMS affected sexual differentiation of these structures.
WHAT THEY FOUND
Several key effects emerged. First, the typical sex difference in hypothalamic volume (larger in men) was present in controls and in offspring of mothers who reported low PNMS but disappeared at higher PNMS levels, indicating disrupted sexual differentiation. Second, greater prenatal hardship was associated with smaller hypothalamic and testicular volume in men. Third, PNMS-exposed men had smaller pituitary glands than control men. Fourth, PNMS-exposed women had more follicles and somewhat larger left ovaries than control women, suggesting polycystic-like characteristics. Notably, many associations were stronger for objective hardship than subjective distress, and some were lateralized (affecting the left gonads).
WHAT IT MEANS
These findings support the idea that prenatal stress alters fetal hormone environments—such as fetal testosterone or its metabolites—affecting how reproductive structures develop. The results suggest sex-specific pathways: high maternal stress may inhibit growth of male reproductive structures while altering certain female reproductive traits. Disrupted sexual differentiation of the brain and gonads could have implications for fertility, puberty, and endocrine function. The study also reinforces the importance of objective stress exposure (independent of maternal subjective distress) in shaping developmental outcomes.
WHAT’S NEXT
Future research should investigate the biological mechanisms linking maternal stress to reproductive outcomes, such as changes in the fetal hormone environment including cortisol and androgen pathways. Larger samples are needed to confirm findings and explore timing effects during pregnancy. Studies should also examine clinical outcomes, such as fertility and reproductive disorders (e.g., polycystic ovary syndrome) and account for post-natal contributions (e.g., use of hormonal contraceptives). Improving imaging methods could allow more precise assessment of small brain regions. Finally, interventions that reduce stress during pregnancy may help mitigate long-term developmental impacts.