What is the first sign of sexual maturation in a male child?

The first sign of sexual maturation in a male child is an increase in testicular size. This physical change indicates the onset of puberty and the beginning of the reproductive maturation process. During this phase, the testes increase in size due to the development of seminiferous tubules and the production of sperm, which is initiated by the rise in testosterone levels.

While growth of body hair and deepening of voice are also important changes that occur during puberty, they happen after the initial growth of the testes. Menarche, on the other hand, is a term specifically related to female puberty and refers to the first occurrence of menstruation, making it irrelevant in the context of male sexual maturation.