When do spontaneous descent of undescended testes rarely occur?

The spontaneous descent of undescended testes, also known as cryptorchidism, typically occurs in the early months of life. The majority of cases will resolve spontaneously, with most testicles descending either before or by the age of 6 months.

By 9 months of age, the likelihood of spontaneous descent significantly decreases, and it is rare for the testes to descend on their own after this period. If the testes have not descended by this time, intervention is usually necessary, often requiring medical or surgical management to ensure proper development and prevent potential complications such as infertility or malignancy later in life.

This understanding aligns with the typical developmental timeline of the testes and the established clinical practices for managing undescended testes in neonates and infants.