Hair cortisol as a biomarker of chronic stress in women with idiopathic infertility

Unexplained infertility, clinically termed idiopathic infertility (II), imposes a significant psychological burden on women, frequently exacerbating states of anxiety and emotional stress. The relationship between chronic psychosocial stress and the hypothalamic-pituitary-adrenal (HPA) axis has been the subject of investigation, with cortisol playing a central role in the biological response to stressful events. Traditionally, serum or salivary cortisol measurements reflect only acute fluctuations of the hormone, making them inadequate for measuring prolonged stress states. Recently, hair cortisol has emerged as a promising biomarker, capable of recording systemic cortisol exposure accumulated over months, providing a more accurate view of the state of hyperactivation or exhaustion of the HPA axis. This study aims to conduct a systematic literature review on the use of hair cortisol as a marker of chronic stress in women with idiopathic infertility and its possible correlation with reproductive outcomes. The methodology was based on a structured search in the SciELO and LILACS databases, selecting studies published in the last decade that investigated the association between hair cortisol levels and the diagnosis or prognosis of infertility. Results show that women with idiopathic infertility frequently exhibit elevated hair cortisol levels compared to fertile control groups, suggesting that chronic stress may modulate fertility through neuroendocrine pathways. It is concluded that hair cortisol is a robust and non-invasive tool for assessing chronic stress, and its inclusion in infertility investigation protocols is necessary to implement multidisciplinary interventions focused on stress management.(AU)