The optimal age for men to have children is between 25 and 35 years old, but this varies from person to person. Research has pointed out that the decline of male gonads – testicular function is not as obvious as that of women, but the male reproductive capacity is gradually declining with age. 30 years old, the number of testicular androgen-producing mesenchymal stromal cells begins to decrease, but because of the enormous compensatory capacity of the testes, the reproductive function will not yet be significantly affected. However, if a disease develops and the state of health declines drastically, reproductive capacity will be greatly impaired. Some underlying reproductive system diseases, such as varicocele and small testicular volume, may not have a significant impact on the fertility of men under 30 years of age, but as they grow older and the disease develops, their fertility will become lower and lower. To summarize, it is recommended that men should preferably complete their fertility between the ages of 25 and 35. If you have any other questions, it is recommended to consult a medical professional for guidance.