Effects of the prenatal environment on cryptorchidism: A narrative review.

Cryptorchidism, the absence of testes from the scrotum, is the most common genital disorder in boys and a risk factor for reduced fertility and testicular cancer. The mechanism responsible for cryptorchidism involves two discrete stages: a transabdominal and an inguinoscrotal phase. These phases of testicular descent are regulated by the prenatal sex hormone environment, including levels of testosterone, insulin-like factor 3, and calcitonin gene-related peptide. Environmental endocrine disruptors, which are unfavorable environmental factors, may also affect testicular descent through prenatal sex hormones. This review examined the effects of environmental factors, particularly environmental endocrine disruptors, such as phthalates, organochlorine pesticides, diethylstilbestrol, bisphenol A, dioxins/dioxin-like compounds, and perfluoroalkyl substances, and parental lifestyles on the risk of cryptorchidism. Although some studies have shown that environmental endocrine disruptors can affect testicular descent by changing the hormonal environment during the prenatal period, no significant association has been established between exposure to environmental endocrine disruptors and the incidence of cryptorchidism. Therefore, the role played by environmental endocrine disruptor exposure (if any) in the pathogenesis of cryptorchidism remains unknown. Further studies are needed to examine these issues.