This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A major international study of the role cortisol plays in reproduction has found it may not be the villain it has been depicted as, and it may actually promote healthy reproduction. The large systematic review, led by Australia's La Trobe University and involving scientists in the United States and Canada, found that while cortisol is often labeled a "stress hormone," it is a normal and potentially supportive part of female reproductive cycles.
The findings are published in the Journal of Experimental Biology. Researchers reviewed almost 70 studies of cortisol across the animal kingdom, including mammals, birds, reptiles, amphibians and fish, searching for information about normal cortisol patterns across the ovarian cycle. They found that 73% of the studies reported a significant change in cortisol during healthy ovarian cycles, with levels often increasing around the time of ovulation, suggesting it is a normal part of healthy female ovarian cycles.
Kerry Fanson, the head of the Wildlife Conservation and Reproductive Endocrinology Lab at La Trobe University, said the findings challenged the simple view that elevated cortisol levels always suppress reproduction—and in fact suggested they are an important part of fertility. "Infertility is a huge issue across the spectrum, not just for humans—it's important for people like dairy farmers who want to know why their cows aren't getting pregnant, or for helping support the survival of endangered species," she said. "While our study didn't include humans, our findings relate to people as the principles are the same." Fanson said the findings meant reproductive scientists could now factor natural cortisol into fertility studies and support better outcomes.
"Our study suggests we've been oversimplifying the role cortisol plays in fertility. Imagine trying to treat diabetes if you didn't think insulin was involved. Recognizing that cortisol plays an important role in reproduction creates new opportunities to diagnose and treat reproductive problems," she said.
Edwards et al., Increases in glucocorticoids are part of healthy female ovarian cycles: a systematic review across vertebrates, Journal of Experimental Biology (2026). DOI: 10.1242/jeb.252436 Journal information: Journal of Experimental Biology Swati Mestri holds a bachelor's degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.
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