In the pre- and anovulatory cycle, estrogens are the primary determinants for the onset of menstruation. Estrogens do not induce ovulation. Estrogen levels rise during the first half of the menstrual cycle. At midpoint in the second half of the cycle, the corpus luteum produces high levels of both estrogens and progesterone. Decline of estrogenic activity at the end of the menstrual cycle commonly brings on menstruation, although the cessation of progesterone secretion is the most important factor in this phase of the mature ovulatory cycle.
Estrogens also affect the psychologic and emotional aspects of feminine behavior.
As estrogen levels increase during the menstrual cycle, women experience a sense of well-being and vigor. In the postmenopausal period, after the decline of endogenous estrogen production, estrogen administration aids in relieving nervous symptoms, such as anxiety, depression and irritability. The treatment of atrophic vaginitis, dyspaneuria and kraurosis vulvae. For many years it has been known that topical or vaginal estrogen therapy would stimulate cell growth and development, improving the epithelial thickness of the vaginal mucosa and increasing secretions. Recent reports have shown that the intravaginal use of topical estrogen creams produces even higher blood estrogen levels than comparable oral doses.