menstruation menstruation menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. the menstrual cycle is characterized by the rise and fall of hormones. menstruation is triggered by falling progesterone levels and is a sign that pregnancy has not occurred. diagram illustrating how the uterus lining builds up and breaks down during the menstrual cycle the first period, a point in time known as menarche, usually begins between the ages of 12 and 15. menstruation starting as young as 8 years would still be considered normal. the average age of the first period is generally later in the developing world, and earlier in the developed world. the typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women. in adults, the range is between 21 and 31 days with the average being 28 days. bleeding usually lasts around 2 to 7 days. periods stop during pregnancy and typically do not resume during the initial months of breastfeeding. menstruation, and with it the possibility of pregnancy, ceases after menopause, which usually occurs between 45 and 55 years of age. up to 80% of women do not experience problems sufficient to disrupt daily functioning either during menstruation or in the days leading up to menstruation. symptoms in advance of menstruation that do interfere with normal life are called premenstrual syndrome (pms). some 20 to 30% of women experience pms, with 3 to 8% experiencing severe symptoms. these include acne, tender breasts, bloating, feeling tired, irritability, and mood changes. other symptoms some women experience include painful periods and heavy bleeding during menstruation and abnormal bleeding at any time during the menstrual cycle. a lack of periods, known as amenorrhea, is when periods do not occur by age 15 or have not re-occurred in 90 days. characteristics further information: menstrual cycle length and duration the first menstrual period occurs after the onset of pubertal growth, and is called menarche. the average age of menarche is 12 to 15 years. however, it may occur as early as eight. the average age of the first period is generally later in the developing world, and earlier in the developed world. the average age of menarche has changed little in the united states since the 1950s. menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. the first day of menstrual bleeding is the date used for the last menstrual period (lmp). the typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults. the average length is 28 days; one study estimated it at 29.3 days. the variability of menstrual cycle lengths is highest for women under 25 years of age and is lowest, that is, most regular, for ages 25 to 39 years. the variability increases slightly for women aged 40 to 44 years. perimenopause is when a woman's fertility declines, and menstruation occurs less regularly in the years leading up to the final menstrual period, when a woman stops menstruating completely and is no longer fertile. the medical definition of menopause is one year without a period and typically occurs between 45 and 55 years in western countries.: 381 menopause before age 45 is considered premature in industrialized countries. like the age of menarche, the age of menopause is largely a result of cultural and biological factors. illnesses, certain surgeries, or medical treatments may cause menopause to occur earlier than it might have otherwise. bleeding menstrual cup filled with menstrual fluid the average volume of menstrual fluid during a monthly menstrual period is 35 millilitres (2.4 us tbsp) with 10–80 millilitres (0.68–5.41 us tbsp) considered typical. menstrual fluid is the correct name for the flow, although many people prefer to refer to it as menstrual blood. menstrual fluid is reddish-brown, a slightly darker color than venous blood.: 381 about half of menstrual fluid is blood. this blood contains sodium, calcium, phosphate, iron, and chloride, the extent of which depends on the woman. as well as blood, the fluid consists of cervical mucus, vaginal secretions, and endometrial tissue. vaginal fluids in menses mainly contribute water, common electrolytes, organ moieties, and at least 14 proteins, including glycoproteins. many women and girls notice blood clots during menstruation. these appear as clumps of blood that may look like tissue. if there was a miscarriage or a stillbirth, examination under a microscope can confirm if it was endometrial tissue or pregnancy tissue (products of conception) that was shed. sometimes menstrual clots or shed endometrial tissue is incorrectly thought to indicate an early-term miscarriage of an embryo. an enzyme called plasmin – contained in the endometrium – tends to inhibit the blood from clotting. the amount of iron lost in menstrual fluid is relatively small for most women. in one study, premenopausal women who exhibited symptoms of iron deficiency were given endoscopies. 86% of them actually had gastrointestinal disease and were at risk of being misdiagnosed simply because they were menstruating. heavy menstrual bleeding, occurring monthly, can result in anemia. hormonal changes this section is an excerpt from menstrual cycle. the menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. the ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. the uterine cycle governs the preparation and maintenance of the lining of the uterus (womb) to receive an embryo. these cycles are concurrent and coordinated, normally last between 21 and 35 days, with a median length of 28 days, and continue for about 30–45 years. naturally occurring hormones drive the cycles; the cyclical rise and fall of the follicle stimulating hormone prompts the production and growth of oocytes (immature egg cells). the hormone estrogen stimulates the uterus lining (endometrium) to thicken to accommodate an embryo should fertilization occur. the blood supply of the thickened lining provides nutrients to a successfully implanted embryo. if implantation does not occur, the lining breaks down and blood is released. triggered by falling progesterone levels, menstruation (a "period", in common parlance) is the cyclical shedding of the lining, and is a sign that pregnancy has not occurred. side effects menstrual health overview this section is an excerpt from menstrual cycle § menstrual health. a human primary ovarian follicle viewed by microscopy. the round oocyte stained red in the center is surrounded by a layer of granulosa cells, which are enveloped by the basement membrane and theca cells. the magnification is around 1000 times. (h&e stain) although a normal and natural process, some women experience premenstrual syndrome with symptoms that may include acne, tender breasts, and tiredness. more severe symptoms that affect daily living are classed as premenstrual dysphoric disorder and are experienced by 3 to 8% of women. dysmenorrhea (menstrual cramps or period pain) is felt as painful cramps in the abdomen that can spread to the back and upper thighs during the first few days of menstruation. debilitating period pain is not normal and can be a sign of something severe such as endometriosis. these issues can significantly affect a woman's health and quality of life and timely interventions can improve the lives of these women. there are common culturally communicated misbeliefs that the menstrual cycle affects women's moods, causes depression or irritability, or that menstruation is a painful, shameful or unclean experience. often a woman's normal mood variation is falsely attributed to the menstrual cycle. much of the research is weak, but there appears to be a very small increase in mood fluctuations during the luteal and menstrual phases, and a corresponding decrease during the rest of the cycle. changing levels of estrogen and progesterone across the menstrual cycle exert systemic effects on aspects of physiology including the brain, metabolism, and musculoskeletal system. the result can be subtle physiological and observable changes to women's athletic performance including strength, aerobic, and anaerobic performance. moods and premenstrual syndrome (pms) this section is an excerpt from premenstrual syndrome. premenstrual syndrome (pms) is a disruptive set of emotional and physical symptoms that regularly occur in the one to two weeks before the start of each menstrual period. symptoms resolve around the time menstrual bleeding begins. different women experience different symptoms. premenstrual syndrome commonly produces one or more physical, emotional, or behavioral symptoms, that resolve with menses. the range of symptoms is wide, and most commonly are breast tenderness, bloating, headache, mood swings, depression, anxiety, anger, and irritability. to be diagnosed as pms, rather than a normal discomfort of the menstrual cycle, these symptoms must interfere with daily living, during two menstrual cycles of prospective recording. these symptoms are nonspecific and are seen in women without pms. often pms-related symptoms are present for about six days. an individual's pattern of symptoms may change over time. pms does not produce symptoms during pregnancy or following menopause. diagnosis requires a consistent pattern of emotional and physical symptoms occurring after ovulation and before menstruation to a degree that interferes with normal life. emotional symptoms must not be present during the initial part of the menstrual cycle. a daily list of symptoms over a few months may help in diagnosis. other disorders that cause similar symptoms need to be excluded before a diagnosis is made. the cause of pms is unknown, but the underlying mechanism is believed to involve changes in hormone levels during the course of the whole menstrual cycle. reducing salt, alcohol, caffeine, and stress, along with increasing exercise is typically all that is recommended for the management of mild symptoms. calcium and vitamin d supplementation may be useful in some. anti-inflammatory drugs such as ibuprofen or naproxen may help with physical symptoms. in those with more significant symptoms, birth control pills or the diuretic spironolactone may be useful. over 90% of women report having some premenstrual symptoms, such as bloating, headaches, and moodiness. premenstrual symptoms generally do not cause substantial disruption, and qualify as pms in approximately 20% of pre-menopausal women. antidepressants of the selective serotonin reuptake inhibitors class may be used to treat the emotional symptoms of pms. premenstrual dysphoric disorder (pmdd) is a more severe condition that has greater psychological symptoms. pmdd affects about 3% of women of child-bearing age. cramps in most women, various physical changes are brought about by fluctuations in hormone levels during the menstrual cycle. this includes muscle contractions of the uterus (menstrual cramping) that can precede or accompany menstruation. many women experience painful cramps, also known as dysmenorrhea, during menstruation. among adult women, that pain is severe enough to affect daily activity in only 2%–28%. severe symptoms that disrupt daily activities and functioning may be diagnosed as premenstrual dysphoric disorder. these symptoms can be severe enough to affect a person's performance at work, school, and in everyday activities in a small percentage of women. when severe pelvic pain and bleeding suddenly occur or worsen during a cycle, this could be due to ectopic pregnancy and spontaneous abortion. this is checked by using a pregnancy test, ideally as soon as unusual pain begins, because ectopic pregnancies can be life‑threatening. the most common treatment for menstrual cramps are non-steroidal anti-inflammatory drugs (nsaids). nsaids can be used to reduce moderate to severe pain, and all appear similar. about 1 in 5 women do not respond to nsaids and require alternative therapy, such as simple analgesics or heat pads. other medications for pain management include aspirin or paracetamol and combined oral contraceptives. although combined oral contraceptives may be used, there is insufficient evidence for the efficacy of intrauterine progestogens. one review found tentative evidence that acupuncture may be useful, at least in the short term. another review found insufficient evidence to determine an effect. interactions with other conditions known interactions between the menstrual cycle and certain health conditions include: some women with neurological conditions experience increased activity of their conditions at about the same time during each menstrual cycle. for example, drops in estrogen levels may trigger migraines, especially when the woman