Sex hormones are mainly secreted by the gonads of the reproductive system. Female sex hormones are mainly secreted by the ovaries, while the adrenal cortex also secretes a certain amount of sex hormones, and the placenta also secretes sex hormones after a woman becomes pregnant, so what are the main roles of female hormones. The most important role of sex hormones is to promote the healthy development of the reproductive system and maintain the secondary sexual characteristics (such as the form and function of the breasts and vulva). Under the action of estrogen and progesterone, women will form a cycle of menstruation, as well as the ovarian cycle of ovulation. The action of estrogen and progesterone causes the development of breast tissue in women. Sex hormones are also the main substances that stimulate sexual desire and realize sexual function. The female body also secretes a small amount of androgens, which play an important role in promoting protein synthesis, bone calcium deposition and bone growth.