STRESS IN THE WOMB LINKED TO FUTURE HEART DISEASE, NEW STUDY FINDS

New research reveals that stress hormones in the womb may interfere with early heart development, increasing the risk of heart disease later in life.

Expectant mothers dealing with high stress or pregnancy complications may unknowingly be affecting their baby’s future heart health, according to a new study from the University of South Australia.

Researchers found that exposure to elevated cortisol — the body’s primary stress hormone — in the womb can disrupt the development of the heart in preterm fetuses, potentially raising the risk of cardiovascular disease in adulthood.

The findings, published in Experimental Physiology, could have implications for the use of synthetic cortisol (often administered to accelerate lung development in premature babies) during pregnancy, as well as for managing maternal stress during the prenatal period.

“When cortisol levels rise too early — either due to maternal stress or medical intervention — it may accelerate heart development in ways that aren’t entirely beneficial,” says lead author Professor Janna Morrison, Head of the Early Origins of Adult Health Research Group at UniSA.

“This could increase the risk of cardiovascular disease many years later.”

The team studied preterm lambs and found that seven days of elevated cortisol exposure led to significant changes in the heart’s molecular structure — affecting signals responsible for growth, energy regulation, and protective heart functions.

“We found that cortisol disrupted key cardiac pathways by altering molecular signals and suppressing glucocorticoid receptors,” says co-author Dr Reza Amanollahi.“

"Given how closely sheep and human hearts develop, it raises important concerns about how prenatal stress might also compromise human infants born prematurely.”

Preterm birth is already known to be a leading cause of neonatal death and is associated with a greater risk of developing heart disease in adulthood.

Cortisol rises naturally toward the end of pregnancy to prepare a baby’s lungs and organs for life outside the womb. But if cortisol spikes too early — due to stress, gestational diabetes, preeclampsia, obesity or placental issues — it may interfere with the normal sequence of development.

“Antenatal corticosteroids are vital for preterm survival,” says co-lead Dr Mitchell Lock.“But our research shows we need to better understand the timing and long-term effects on the heart to help improve outcomes for preterm babies.”

The study highlights a growing area of research connecting early-life stress with adult chronic disease — and the need for careful monitoring and support for women at risk of early delivery.