Menstruation usually starts at the age of 13 and stops by itself at the age of 49, which lasts about 35 years. Except for special circumstances such as pregnancy, menstruation basically occurs once a month. How many days is a normal menstrual cycle? Menstruation refers to regular, cyclical uterine bleeding. It is also known as menstruation, moon water, moon letter, regular period, etc. Strictly speaking, along with this bleeding, there should be follicle maturation, ovulation and corpus luteum formation in the ovaries and a change in the endometrium from hyperplasia to secretion. Menstruation should have a normal cycle, period, volume, color and quality of menstruation. The normal menstrual cycle should be 20 to 36 days, which varies from person to person. Each woman has her own menstrual cycle, and we generally think that the cycle is either 28 or 30 days. But in fact, each person’s menstrual cycle is very different, someone as little as 20 days, there are people as much as 36 days, this period are considered normal. According to the relevant departments of clinical research statistics, really every time can be in 28 days to 30 days to a menstrual period of about 10%. As long as the interval of each menstrual cycle is the same, it is normal. Irregularly early or late periods are not normal and may be a symptom of some disease, which requires accurate records of the time each time, otherwise it is difficult to deduce from impressions only. The first day of bleeding (i.e., the onset of menstruation) is called the beginning of the menstrual cycle, and the interval between the first day of two menstrual periods is called a menstrual cycle, usually 28-30 days, which is about the same as a lunar month. The length of the cycle varies from person to person, but occasionally it can be considered normal if it is not more than 7 days early or late, i.e. the menstrual cycle should not be less than 21 days and not more than 35 days. Menstruation will stop during pregnancy and lactation. Causes of short menstrual cycle The normal menstrual cycle of women is usually 28-30 days, although there is individual variability in cycle length, there is a threshold value for reference, and it is generally considered that a menstrual cycle shorter than 21 days is considered abnormal. The main causes of short menstrual cycles are ovarian hypofunction, luteal insufficiency, and uterine fibroids. 1. Ovarian hypofunction The ovaries are an important reproductive organ of women and play a very important role in a woman’s life. From puberty to pre-menopause, the ovaries often repeat cyclical changes in form and function. When these changes stop, the ovaries stop producing eggs, marking the beginning of menopause. If ovarian function begins to diminish, then female estrogen will decrease, which directly leads to a decrease in menstrual volume and shorter menstrual cycles. 2, dysfunctional uterine bleeding disorder Dysfunctional uterine bleeding is a gynecological disease, which refers to abnormal uterine bleeding caused by the dysfunction of the reproductive endocrine axis, divided into anovulatory and ovulatory uterine bleeding, which may lead to more or less menstrual volume, and therefore it is also a cause of shorter menstrual cycle. Luteal insufficiency The menstrual cycle includes the luteal phase. Luteal insufficiency refers to the insufficient endocrine function of the corpus luteum formed after ovulation, resulting in insufficient secretion of progesterone and low endometrial secretion, making the relatively fixed luteal phase shorter and eventually leading to shorter menstrual cycles. 4.Uterine fibroids Uterine fibroids are the most common benign tumors in female reproductive organs. Some patients with uterine fibroids may experience frequent menstruation, and their menstrual cycle may become shorter due to frequent menstruation. 5.Ovulatory bleeding Ovulation is a part of the menstrual cycle, and some women with more ovulatory bleeding may also show frequent menstruation, which may affect normal menstruation, and this is also a cause of short menstrual cycle One of the reasons. Causes of long menstrual cycles The normal menstrual cycle is 21-35 days, with an average of 28 days. It is usually normal to have your period about a week early or late. There are many reasons for long menstrual cycles in some women, which can be divided into the following categories: central nervous system-hypothalamus abnormalities; pituitary abnormalities refer to pituitary gland lesions that cause abnormal gonadotropin secretion, both congenital and acquired lesions; ovarian abnormalities due to congenital dysplasia of the ovaries or abnormal ovarian function or secondary lesions that cause abnormal menstruation. 1, endometriosis The occurrence of endometriosis can affect the contraction of the myometrium or the enhancement of the endometrium, and the enhancement of the endometrium will lead to prolonged shedding of the endometrium, resulting in excessive menstrual cycles or prolonged periods. 2, placement of birth control device Placement of birth control device, the endometrium is compressed by the ring, and inflammatory infiltration of cells occurs, which also tends to cause prolonged periods. 3.Uterine smooth muscle tumor Especially submucosal myoma, which is due to the expansion of the uterine cavity area, resulting in abnormal contraction of the uterus, which may lead to excessive menstrual cycles and prolonged periods. 4.Uterine dysfunctional bleeding Such as anovulatory dysfunctional uterine bleeding disorder and irregular shedding of endometrium, both of which are caused by endocrine dysfunction and result in long menstrual cycles. 5. Chronic hypertrophy of the uterus Due to pelvic stasis and continuous increase of ovarian estrogen, the myometrium becomes hypertrophic, forming chronic hypertrophy of the uterus, causing excessive menstrual cycles and prolonged menstrual periods. 6. Blood disorders such as thrombocytopenic violet epilepsy and aplastic anemia are often accompanied by the onset of menstrual cycle, which can make the period prolonged if there is severe uterine bleeding. Other such as chronic anemia, chronic hepatitis, cirrhosis of the liver, nephritis, etc., can make the blood vessel wall fragile and increase permeability causing bleeding. 7, other pelvic inflammatory disease, endometrial femoral polyps, uterine inflammation, etc. all factor endometrial femoral poor blood circulation, degenerative necrosis or pelvic stasis, etc. cause excessive menstrual cycles and prolonged periods.