Cryptorchidism is as common as type 2 diabetes or celiac disease. Boys with congenital cryptorchidism are atincreased risk of infertility and testicular cancer. Zika syndrome, which affects pregnant women, is associated with ahigh incidence of undescended testes in the infant, accompanied by epididymal anomalies. Zika and influenza virusinfections during pregnancy trigger a strong anti-inflammatory immune response and elevated estradiol levels.Elevated estradiol and α-fetoprotein in syncytiotrophoblasts from women who have given birth to cryptorchid boysare indicative of increased estradiol levels in the fetus. Here, I present a hypothesis that hypogonadotropichypogonadism, cryptorchidism, and retarded epididymal development may be due to elevated fetal estradiol levelscaused by viral infection during pregnancy. Download complete article