The first menstruation is the sign of puberty and the beginning of the cyclic regulation of the female reproductive organs. The physiological changes of menstruation are a very complex process, and a very brief description of this cycle is given here. Generally speaking, the menstrual cycle is 28-30 days long, and it may be normal for it to be advanced or pushed back. As long as the body, especially the pituitary gland and the ovaries, undergoes the corresponding cyclic changes, there is generally no need to make adjustments to a slightly shorter or longer menstrual cycle. The pattern of the menstrual cycle is roughly like this. Starting from the onset of menstruation, along with the gradual development of follicles in the ovaries, estrogen synthesis increases. An important function of estrogen is to repair the uterine lining, which is repaired and intact, and menstruation stops; thereafter the amount of estrogen continues to increase, and the uterine lining continues to thicken. You will feel an increase in vaginal discharge, sometimes it will be obvious that the discharge is like egg white, transparent, sticky, and can be stretched to a long time, this is the follicle is well developed and will soon be mature, in the early stage of follicle development, usually there will be more than a dozen follicles will be competing for the development of the follicles together, and generally, only one has the opportunity to develop the best, known as the dominant follicle, and only the dominant follicle has the hope of development in a menstrual cycle. Mature ovulation, ovulation usually occurs 14 days before the next menstrual period, some people who are more sensitive, will feel a soreness and falling sensation in the lower abdomen. Sometimes a very small amount of vaginal bleeding occurs during ovulation, called ovulation bleeding, and these are normal. The clear egg white-like discharge disappears immediately after ovulation, when estrogen levels are low. An important change after ovulation is the formation of something called corpus luteum at the rupture left after ovulation on the ovary. The corpus luteum can synthesize estrogen and progesterone, which is a kind of progesterone, and under the influence of these two hormones, the endometrium remains thick and has increased moisture to prepare for the possible fertilization of the egg to be planted as if the soil has to be loosened and fertilized before sowing, which is conducive to planting of the pregnant egg. During this period, as the hormone level increases, breast swelling and pain may occur, because if there is no conception, the corpus luteum has a life span of only about 14 days, so the thick lining needs a lot of hormonal support, once the hormonal support is lost, the lining becomes ischemic and begins to peel off, which is the next cycle of menstruation. Therefore, the onset of menstruation is caused by a decrease in hormone levels. It should be emphasized that it is not “menstruation = ovulation”, if the follicle is immature, there is no ovulation, only estrogen accumulates irregularly, and finally the endothelium is too hypertrophic, and there is not enough hormone to maintain the integrity of the endothelium, bleeding will also be formed, which is also known as menstruation, but this kind of menstruation is often manifested as an irregular cycle, the menstrual period is too long or too short, the amount is more or less, and so on. But this kind of menstruation often shows irregular cycle, too long or too short menstruation period, more or less amount and so on. So prolonged menopause and administration of progesterone therapy is giving an endometrial secretory response that occurs after discontinuation of the medication with a drop in hormone levels that mimics hormonal withdrawal bleeding, where vaginal bleeding occurs a few days after discontinuation of the medication rather than during the period of medication. Occasional anovulation does not matter, and do not worry about the side effects of progesterone, it is the lack of hormones that should be secreted by the body that leads to menstrual disorders, supplementation is given without harm, but at this point the progesterone only solves the problem once, and after the advent of withdrawal bleeding is back to square one.