Testosterone is stimulated by luteinizing hormone (LH) from the pituitary gland. It regulates the production of sperm, as well as the growth and maintenance of the male sex organs. Testosterone also stimulates the development of the male secondary sex characteristics, including growth of facial and pubic hair. It causes the deepening of the male voice by enlarging the larynx.

The estrogens are stimulated by follicle-stimulating hormone (FSH) in the pituitary. They help regulate the menstrual cycle and the development of the mammary glands and female secondary sex characteristics. Luteinizing hormone (LH) stimulates the secretion of progestins. Progesterone prepares the uterus for the arrival of a developing embryo in case fertilization occurs. It also accelerates the movement of an embryo to the uterus. Relaxin helps enlarge and soften the cervix and birth canal at the time of delivery. It causes the ligaments of the pubic symphysis to be more flexible at the time of delivery.