Melatonin in the Treatment of Female Infertility: Update on Biological and Clinical Findings

Many experimental and clinical studies published so far demonstrate that melatonin-produced mainly by the pineal gland located deep in the middle of the brain, between the two cerebral hemispheres, and in smaller quantities in a number of other organs and cells of the body-can be successfully used to treat different types of human female infertility. To accomplish this, melatonin acts mainly on the ovary, the uterus, and the preimplantation embryo, through its antioxidant, anti-inflammatory, and immunomodulatory effects, in addition to acting as a hormone and cytokine modulator. In particular, it increases oocyte developmental competence and uterine receptivity for the implanting embryo, improves placental health and function, prevents immune rejection of the implanting embryo and spontaneous pregnancy loss, and alleviates symptoms of endometriosis and adenomyosis. Yet, the use of melatonin in these contexts remains relatively limited, despite its convincing safety profile. This may be partly due to the fact that pertinent data concerning the use of melatonin in female infertility treatment are dispersed across various specialized scientific and medical journals, making it difficult for doctors and embryologists confronted with female infertility issues to access all of them. Therefore, this article was written to provide data that are easily understood. It draws from recent findings collected from different specialized journals focused on the molecular mechanisms of action, the clinical data, and the safety of this multifaceted biomolecule in the treatment of female infertility.