Cortisol Exposure in Womb Linked to Heart Development Risks

A recent study led by researchers at the University of South Australia (UniSA) has uncovered critical insights into how exposure to elevated levels of cortisol, the body's primary stress hormone, during preterm fetal development can disrupt normal heart development and potentially increase the risk of cardiovascular disease in later life. Published in the journal *Experimental Physiology* on June 23, 2025, the findings point to significant alterations in molecular pathways that are crucial for healthy cardiac development.

The research team, headed by Professor Janna Morrison, revealed that preterm lambs exposed to artificial cortisol levels reflected those typically seen in late pregnancy experienced substantial changes in the molecular structure of their hearts. "Our research sought to understand how cortisol—whether naturally elevated or via synthetic versions used to promote lung development—affects the developing cardiovascular system in preterm fetuses," stated Morrison.

Cortisol naturally increases in late pregnancy, aiding in the maturation of fetal organs, but an early surge—due to maternal stress or medical interventions—may accelerate heart development in ways that are detrimental, leading to heightened cardiovascular risks later in life.

The study's methodology involved administering cortisol over a seven-day period to preterm sheep fetuses to simulate late gestation hormone levels. This approach allowed researchers to analyze the impact on signaling molecules involved in cardiac growth and metabolism. Co-author Dr. Reza Amanollahi noted, "We found that elevated levels of cortisol during early heart development disrupt key cardiac pathways by suppressing glucocorticoid receptors and altering molecular signals involved in growth, energy metabolism, and cardio-protection."

These findings raise alarms about the implications for human infants born prematurely. Dr. Mitchell Lock, another key contributor to the study, emphasized the necessity of closely monitoring the use of antenatal corticosteroids during pregnancy, despite their established role in improving neonatal survival rates. He added, "We hope these findings will also help refine the clinical care of preterm babies to support better long-term outcomes."

The research underscores the importance of understanding prenatal stressors and their potential lasting impacts on cardiovascular health. Cardiovascular disease remains the leading cause of mortality globally, and this study contributes to a growing body of evidence indicating that early life factors can significantly influence heart health in adulthood.

In conclusion, the implications of this study extend beyond immediate clinical practices; they point towards a need for a multifaceted approach in prenatal care that considers the long-term health of both mothers and their children. As the field of perinatal health continues to evolve, it becomes crucial to integrate these findings into guidelines that govern the management of pregnancies complicated by stress and other risk factors.