Is Cortisol useful for fertility?

Cortisol, the primary stress hormone, can influence fertility through multiple pathways. Chronically elevated cortisol levels are associated with menstrual irregularities, reduced libido, and poorer egg quality, mainly via inhibition of GnRH secretion and disruption of ovarian hormone balance. However, the evidence is complex: cortisol follows a strong circadian rhythm, and single measurements (e.g., in saliva or blood) are insufficient to diagnose fertility issues. The MyBody-X resource on cortisol emphasizes that a single test is not diagnostic and that lifestyle factors such as sleep hygiene and stress management play a larger role. There is no strong, direct evidence from randomized trials validating cortisol tests as fertility markers. Using cortisol as a biomarker for fertility remains speculative and should not be the sole basis for decisions. A holistic approach with medical guidance is recommended.