When a child reaches the stage of puberty, he or she experiences several hormonal changes. At the start of puberty, one's brain produces a hormone called gonadotropin-releasing hormone (GnRH), which sets off the pituitary gland - the control system for several other hormones. This therefore results in the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) into the bloodstream, leading to different changes in the male and female bodies. A female body starts producing estrogen, whereas a male body makes testosterone.