Cryptorchidism is one of the common congenital anomalies of the genitourinary system in children, which refers to the failure of the testicles to descend into the scrotum, including incomplete testicular descent and testicular ectopia. The testes normally develop in the abdominal cavity of the fetus and gradually descend into the scrotum in the last 3 months. When the testes cannot move into the scrotum normally, it is called incomplete testicular descent, also known as cryptorchidism. The causes of cryptorchidism in babies are complicated, and the common causes are as follows: (1) Genetic factors: For example, the grandfather and father of the child are cryptorchidism patients. (2) Environmental factors: Drugs used during pregnancy, such as progesterone and estrogen, can interfere with the baby’s own testosterone secretion in the testes and affect the descent of the testes. (3) Inflammatory infections during embryonic period: such as intrauterine infections, which can affect the descending pathway of the testis and lead to fibrous tissue cords, pulling the testis to fail to descend normally. (4) Abnormality or absence of the testicular lead band that introduces the testis into the scrotum, to the extent that the testis cannot descend to the scrotum from its original position. (5) Congenital testicular hypoplasia makes the testis insensitive to gonadotropins and loses its descending power. (6) Luteinizing hormone-releasing hormone produced by hypothalamus, which makes the pituitary gland secrete LH and follicle-stimulating hormone FSH lacking, can also affect the descending power of testes. Therefore, the appearance of cryptorchidism in the baby may be related to the mother, such as the application of birth control drugs, progesterone and estrogen in early pregnancy, which interfere with the fetus’ own testosterone secretion. Intrauterine infection during pregnancy, which affects the descending pathway of testicles, etc. may lead to cryptorchidism in the baby. Of course, it can also be related to other factors besides the mother’s factor.