At first glance, mumps and fertility don’t seem to go hand in hand, do they? Is there really a relationship between the two? The answer is yes, so when it comes to the connection between the two, it’s time to talk about the mumps virus, the main culprit of mumps. Mumps is divided into bacterial mumps and viral mumps. Viral mumps, also known as mumps, is caused by the mumps virus, and humans are its only natural host. It is characterized by non-suppurative swelling of the parotid gland and can invade various glandular tissues or almost all organs of the nervous system, liver, kidneys, heart and joints, and can often cause complications such as meningoencephalitis, orchitis, ovarian inflammation and pancreatitis. The specific process is as follows: the virus first infects the mucosa of the upper whistle and replicates within its epithelium. Then, the replicated virus is released into the bloodstream, forming a viremia that is localized in the endothelium of the parotid tubules, which is what triggers mumps. The virus then continues to replicate and proliferate into the bloodstream to form a second viremia, which infects other organs, such as the testes. Therefore, mumps can trigger mumps orchitis and is very common in adolescent and adult males. Although mumps orchitis is self-limiting, the damage to testicular tissue is irreversible. Patients experience early testicular pain, swelling, redness of the scrotal skin, and increased skin temperature, with testicular atrophy occurring in about 30% to 50% of patients after the acute phase. Of these, about 13% of patients show reduced fertility and 30% to 87% of patients with bilateral mumps orchitis show male infertility, which reduces male reproductive function to some extent and will lead to azoospermia in severe cases. Mumps orchitis and male reproductive function are closely related, and there are no effective methods of fertility protection for this disease. There are many patients who develop spermatogenic dysfunction even after aggressive treatment in the acute phase. Therefore, early detection and early intervention is essential. In young children, once mumps virus infection is diagnosed, changes in testicular texture and volume should be monitored at all times and appropriate symptomatic treatment should be given promptly in the early stages of testicular pathology.