Although small amounts of sex hormones are secreted by the adrenal glands in both males and females, for the most part these hormones are produced by the sex glands. Estrogens and progesterone are the female hormones responsible for secondary sex characteristics such as development of the breasts and maintenance of the lining of the uterus. Testosterone (androgen) is the corresponding male hormone. It is responsible for secondary sex characteristics such as facial hair, a deepened voice, and the maturation of external genitalia.
Testosterone reduces elimination of protein from the body, thereby producing an increase in muscle size. Athletes sometimes take drugs called anabolic steroids (which are chemicals similar to testosterone) for this effect, but using medication for this purpose is dangerous, since anabolic steroids can adversely affect the heart, the nervous system, and the kidneys and cause long-term damage.
Most oral contraceptives (birth control pills) combine estrogen and progestin (natural or synthetic progesterone), but some contain only progestin. Examples of progestin-only contraceptives include the Norplant implant and the Depo-Provera contraceptive device. Progestin aids in preventing ovulation, alters the lining of the uterus, and thickens cervical mucus -- processes that help to prevent conception and implantation. The estrogen in birth control pills prevents egg production. Oral contraceptives have many side effects, so their use should be discussed with a physician.
Conjugated estrogens are occasionally used in hormone replacement therapy to treat more severe symptoms of menopause in women whose bodies are no longer able to produce estrogen in sufficient quantities. However, they are no longer recommended for long-term treatment or replacement therapy in most patients.
Medroxyprogesterone is used to treat uterine bleeding because of its ability to induce and maintain a lining in the uterus that resembles the lining produced during pregnancy. It also suppresses the release of the pituitary hormone that initiates ovulation, and it is used for menstrual problems.