Bugs and babies: How gut microbiota affect infertility? A narrative Review

Infertility is a disease of the reproductive system which is defined as the inability to conceive after more than 12 months of unprotected intercourse. It affects millions of people and has far-reaching impacts on quality of life, sexual dysfunction, marital impact, and societal implications. Despite advancements in understanding infertility, the cause of infertility in around 28% of cases remains unclear. This review addresses the pivotal relation between Gut microbiota (GM) and infertility. GM is now believed to interplay with the human body at different levels and is essential for our well-being. The abnormal translocation of GM to the systemic circulation, known as dysbiosis triggers an over-stimulated immune response associated with a marked increase in pro-inflammatory cytokines. This inflammatory situation may disrupt the hypothalamic-pituitary-gonadal axis and lead to disseminated inflammation ending in adhesions and obstructive lesions of the reproductive tract. Dysbiosis can also predispose individuals to obesity and insulin resistance, where both are risk factors for diabetes, hypertension, polycystic ovary syndrome (PCOS), impaired spermatogenesis, erectile dysfunction, and infertility. GM has an inevitable role in the pharmacokinetics of many drugs and can regulate the expression of many cytochrome P450 enzymes and several transporters. Further research is needed to validate the possible implication of GM in the pathophysiology of infertility, the efficacy of infertility medications, and the potential of GM-based therapies to treat infertile couples.