Menstruation is the monthly shedding of tissue and blood from the uterus. It is the most visible part of the menstrual cycle. Girls usually begin menstruating around the age of 12 or 13 years, but can begin menstruating as young as age 9.
The menstrual cycle is a result of the complex interaction of several hormones. Many hormones are involved, but the four major ones are follicle stimulating hormone (FSH), luteinizing hormone (LH), estrogen and progesterone. The interaction of these hormones generally affects two areas of the reproductive system the most: the uterus and the egg follicles in the ovaries.
The average menstrual cycle lasts about 28 days, but may range from 21 to 35 days. The menstrual period usually lasts about five days each month for most girls. During the menstrual period, blood comes out from the vagina. The amount ranges from a couple of tablespoons to a half-cup or more daily. Girls use various products to absorb menstrual flow, including panty liners, tampons and pads.
During the first few years of menstruation, a girl’s period may be irregular. Some girls may only have three or four periods a year. Within about two years of first menstruating, girls generally develop a more regular monthly cycle.
Menstruation can cause problems ranging from mild discomfort to pain. Some girls have physical and emotional symptoms before menstruating that are severe enough to be classified as premenstrual syndrome (PMS). In addition, many girls experience cramps during menstruation. These cramps tend to affect the lower abdomen, but they may also affect the back or the thighs.
Several other problems may be associated with menstruation. Pain during menstruation is called dysmenorrhea. Amenorrhea is the lack of menstruation. Very heavy bleeding during menstruation is called menorrhagia, which is usually due to an imbalance between levels of estrogen and progesterone.
In some cases, discomfort associated with menstruation can be treated with over-the-counter pain relievers or other techniques, such as warm baths. However, more serious menstrual problems may require prescription medications, surgery or both.
Parents and girls may feel uncomfortable about the prospect of discussing menstruation. However, it is important that this conversation take place before a girl’s teenage years and preferably during middle childhood.
About menstruation
Menstruation is the monthly shedding of tissue and blood that is the most visible part of the menstrual cycle. The menstrual cycle involves all of the woman’s reproductive organs. It is an indicator of good health for reproductive-aged girls and women and also prepares the body for pregnancy.
Girls usually begin menstruating around the age of 12 or 13, but can begin menstruating as young as age 9. In some cases, girls may begin menstruation before age 9 (precocious puberty). Although parents may feel uncomfortable about the prospect of discussing menstruation with their daughters, this conversation is crucial before the girl begins having her monthly cycle. The American Academy of Pediatrics (AAP) recommends discussing puberty, including menstruation, with both boys and girls around age 8 or 9.
The uterus (womb) is a fist-sized, hollow organ in the lower abdomen that can expand to accommodate a growing fetus. The bottom of the uterus (cervix) meets the top portion of the vagina, the tube that leads outside the body. Menstrual blood leaves the body through the vagina. The lining of the uterus (endometrium) includes blood vessels, glands and tissue that grow and thicken to support a fetus during pregnancy. When pregnancy does not occur, the endometrium breaks down and is shed each month during menstruation.
Each fallopian tube extends from the top of the uterus to an ovary, the organs that produce the woman’s eggs. Every month, a mature egg leaves one of the ovaries and travels through the fallopian tube to the uterus. If the egg is fertilized by a sperm, it can implant in the endometrium of the uterus and develop into an embryo. If the egg is not fertilized, it disintegrates and is absorbed into tissue or leaves the body with the menstrual flow.
The first menstrual period (menarche) is part of the sexual development girls go through during puberty. In the early 1900s, girls were likely to have their first menstrual periods around the age of 14 or 15 years. However, improved nutrition and other factors have resulted in girls getting their periods earlier, typically around the age of 12 or 13, but sometimes as early as age 8 or as late as age 16. Many factors influence when a girl first begins to menstruate, including genetics and lifestyle choices, such as excessive exercise (which can deprive a female’s body of the calories, vitamins and minerals it needs to menstruate).
In most cases, girls begin to menstruate about two years after their breasts start to grow. In other cases, this pattern is reversed. A girl may experience a thick, white discharge from her vagina for several months before her first period.
During the first few years of menstruation, a girl’s period may be irregular (anovular). Some girls may only have three or four periods a year. Within about two years of first menstruating, girls should settle down to a more regular monthly cycle. The average menstrual cycle lasts about 28 days, but may range from 21 to 35 days. Normal cycle length varies among women and for a particular woman at different times in life.
The menstrual period usually lasts about five days each month for most girls. However, it can last anywhere from two to eight days. The flow of menstrual blood may be heavy for several days and then light. It may vary in volume and length from month to month. The use of birth control pills may make menstrual periods lighter and shorter.
Girls use various products to absorb menstrual flow. Sanitary napkins (pads) are worn inside the panties. Tampons are inserted into the vagina. Both are made of cotton or another absorbent material. Pads or tampons should be changed frequently (every few hours). When girls first start menstruating, they may prefer to use pads instead of tampons. Girls who use tampons should not find them uncomfortable if the tampon is properly inserted.
Menstruation continues monthly for most girls and women in their reproductive years. Pregnancy interrupts menstruation because the endometrium must nourish the growing fetus. Menstruation resumes after childbirth, sometimes taking several months to return to a normal cycle. Breastfeeding may also affect the return of menstruation.
By about age 50, women’s estrogen levels begin to decrease. The ovaries can no longer ovulate (produce eggs) regularly and eventually women stop menstruating. One year without a period is called menopause. A woman in menopause cannot become pregnant. Surgical removal of the ovaries may also cause a woman to reach menopause immediately, regardless of age. Many women experience several years of transition to menopause (called perimenopause), where menstrual periods may become less frequent.
The menstrual cycle
The menstrual cycle is a result of the complex interaction of several hormones. Many hormones are involved, but the four major ones are follicle stimulating hormone (FSH), luteinizing hormone (LH), estrogen and progesterone. The interaction of these hormones generally affects two areas of the reproductive system the most: the uterus and the egg follicles in the ovaries.
The menstrual cycle can be divided into two major phases:
The follicular phase. This phase includes the first half of the menstrual cycle, beginning with the menstrual period and ending with ovulation. In a 28-day cycle, this includes the first 14 days. The first day of the menstrual period is counted as day one of the cycle. The uterine lining (endometrium) is shed during the menstrual period for about the first five days of the follicular phase.
Two hormones are dominant during this follicular or proliferative phase:
Follicle stimulating hormone (FSH). Produced in the pituitary gland in the brain. FSH stimulates about 15 to 20 egg follicles to begin developing in one ovary. FSH stimulates the follicle development and also stimulates the follicles to produce estrogen.
Estrogen. Produced by the growing follicles. As estrogen reaches a certain level, it causes the endometrial lining (which was just shed as menstrual blood) to begin to grow again. As it rises, the increased estrogen level eventually triggers a stop in FSH production, which prevents more follicles from developing.
During the follicular phase, one developing egg follicle becomes larger than the others (dominant follicle). At about day 14, the estrogen from this follicle triggers a surge and release of LH from the pituitary gland. This triggers ovulation. The egg follicle bursts and releases the mature egg into the fallopian tube.
The luteal phase. Includes the remaining 14 days of the menstrual cycle (when a girl has a 28–day cycle), beginning with ovulation and ending with the start of the next menstrual period. Two other hormones are dominant during the luteal phase:
Luteinizing hormone (LH). Produced by the pituitary gland. Small amounts of LH are produced early in the follicular phase, but the later surge of LH causes ovulation. After ovulation, LH acts on the empty egg follicle, now called the corpus luteum. The corpus luteum secretes small amounts of estrogen and greater amounts of progesterone.
Progesterone. Produced by the corpus luteum. Progesterone promotes the growth and development of the endometrium to receive a fertilized egg. The progesterone level peaks at about day 21 of a 28-day cycle. If there is no fertilized egg, progesterone levels decrease, causing the uterine lining to begin to break down several days later. This subsequently results in menstruation.
The production of estrogen also decreases after ovulation, as the follicles degenerate. With less estrogen and progesterone to promote endometrial development, the uterine lining breaks down enough to be shed by the end of the luteal phase at day 28. This begins the next menstrual period and returns the menstrual cycle to day one.
The days in the middle of the menstrual cycle, near ovulation, are the most likely time for a girl to get pregnant during sexual intercourse. However, in some cases, ovulation occurs at different times in the cycle. The normal menstrual cycle length variability in girls and women makes it difficult to precisely identify where one girl is in her particular cycle.
If the egg is fertilized in the fallopian tube, it continues to the uterus. The enriched endometrium provides a place for the fertilized egg to implant. It does not shed and leave the body. This missed period may be the first sign that a girl is pregnant.
However, some women may experience a small amount of spotting or bleeding very early in the pregnancy, about 10 to 14 days after fertilization, which may be mistaken for menstruation. This is known as implantation bleeding and occurs when the fertilized egg first attaches to the lining of the uterus. This type of bleeding is usually a bit earlier and lighter in color than a usual period and does not last long.
Problems associated with menstruation
Menstruation can cause problems ranging from mild discomfort to pain. Some body changes during the monthly cycle are normal, including breast tenderness or some discomfort just before menstruation.
Some girls have physical and emotional symptoms before menstruating that are severe enough to be classified as premenstrual syndrome (PMS). Symptoms associated with PMS include:
Acne
Backaches
Bloating
Sore breasts
Digestive problems (e.g., constipation, diarrhea)
Depression
Difficulty concentrating
Difficulty handling stress
Fatigue
Food cravings
Headaches
Irritability
PMS is believed to be the result of changes in a girl’s hormone levels. It usually is most severe about a week before a girl’s menstrual cycle begins and ends once a period starts. In most cases, PMS does not appear until several years after a girl’s menstrual cycle begins.
Discomfort may also be present during menstruation. Girls often experience cramps during menstruation. These cramps tend to affect the lower abdomen, but they may also affect the back or the thighs. Cramps may be caused by hormone-like substances known as prostaglandins that cause the muscles of the uterus to contract. In most cases, cramps last for only a day or two. They may be dull and achy, or sharp and intense. As girls get older, cramps often become less common.
Pain during menstruation is called dysmenorrhea. However, physicians generally use the term to refer to severe menstrual pain. There are two types:
Primary dysmenorrhea. More common in teens, it is the result of large amounts of prostaglandins rather than disease or another condition. It leads to nausea and vomiting, headaches, backaches, diarrhea and severe cramps. Symptoms tend to last for just a day or two.
Secondary dysmenorrhea. Result of pain from gynecologic conditions such as polyps, endometriosis (tissue normally found only inside the uterus grows elsewhere), pelvic inflammatory disease (PID) and adenomyosis (uterine tissue that grows into the muscular wall of the uterus).
Girls who have particularly painful or long periods (such as those that last more than 10 days) are urged to consult a physician, such as a gynecologist (physician who specializes in the female reproductive system).
During menstruation, prolonged tampon use has been associated with an extremely rare infection called toxic shock syndrome (TSS). To avoid TSS, girls should follow the tampon package instructions, change their tampons frequently and use the lowest absorbency tampon possible for their menstrual flow.
Amenorrhea is the lack of menstruation. Primary amenorrhea refers to girls who have not experienced their first periods. A girl who has not had her first period by age 16 should consult her physician. Secondary amenorrhea refers to someone who has menstruated previously, but has stopped. The most common reason to miss a period, once the menstrual cycle has become regular for the individual girl, is pregnancy. Girls who have gone six months without a period should see a physician. In addition, any girl who is sexually active is urged to see a physician if she misses even one menstrual period.
Irregular periods may indicate hormonal imbalances or such conditions as polycystic ovarian syndrome (PCOS).
Girls may also experience very heavy bleeding (menorrhagia), most often due to an imbalance between levels of estrogen and progesterone in the body that allows the endometrium to build up excessively before it is shed. This condition is fairly common in girls, because many adolescents have slight hormone imbalances during puberty. Girls who have menorrhagia may soak through at least one sanitary napkin an hour for several hours in a row, or may have periods that last longer than one week. Girls who have menorrhagia may begin to withdraw socially as they become afraid of an inability to control bleeding in public situations.
Some girls experience vaginal bleeding between periods (metrorrhagia). This may be a symptom of some sexually transmitted diseases, uterine abnormalities such as cancer, polyps or uterine fibroids. Other potential sources of menorrhagia or metrorrhagia include:
Stress
PCOS (a hormonal disorder in which excessive amounts of androgens [male hormones such as testosterone] are produced by the ovaries)
Birth control pills with inadequate doses of hormones for the patient
Trauma to the cervix, vagina or vulva
Clotting disorders
Inflammation or infection of the vagina or cervix
Thyroid conditions
Menorrhagia and metrorrhagia may be controlled by using birth control pills.
Girls should consult their physician about any menstrual conditions that change quickly or become progressively worse. Missed or irregular periods or abnormal vaginal bleeding also indicate a need for medical consultation.
In diagnosing menstrual problems, the physician will perform a complete physical examination and compile a thorough medical history. Other procedures that may be used include a pelvic exam, a Pap smear (a procedure that collects cells from the cervix), blood tests to check hormone levels, and urine or stool tests.
Treating/preventing menstruation problems
Menstruation can cause great discomfort for some girls. In many cases, pain-relieving medications can help reduce symptoms such as cramps. However, these medications should not be taken without first consulting a physician. Hot baths or use of heating pads or hot water bottles can also ease cramps.
Other steps that can be taken to reduce discomfort associated with menstruation include:
Dietary changes. Eating fruits and vegetables and reducing intake of salt and caffeine may help. Chips, crackers and other processed foods should also be avoided.
Supplements. Taking supplements with magnesium, B-complex vitamins and calcium may reduce symptoms. However, these should not be taken without first consulting a physician.
Regular exercise. Brisk walks, bike rides, yoga and other exercise can release endorphins that may make menstruating girls feel better.
More serious menstrual problems that require medical care can be treated with prescription medications (e.g., birth control pills or other medications that contain estrogen or progesterone) or surgery (e.g., to remove uterine polyps or fibroids).
Discussing menstruation with your daughter
Parents and girls may feel uncomfortable about the prospect of discussing menstruation. However, it is important that this conversation take place before a girl’s teenage years. The American Academy of Pediatrics (AAP) recommends discussing all the aspects of puberty with both boys and girls during middle childhood. Girls (and boys) who do not learn about menstruation from their parents may hear misinformation on the topic from peers or other sources.
Parents may find a natural opening to discuss menstruation when their daughter begins health lessons and sex education classes at school. Or, parents can discuss menstruation with their daughter shortly before a doctor’s appointment by explaining that the physician may ask whether she has started menstruating.
It is usually better to break the topic up into several conversations rather than simply trying to disclose all the information about menstruation in a single discussion. Dividing the subject matter will make it less overwhelming for the daughter who is trying to absorb this information. Parents are urged to ask their daughters what they already know about menstruation. Girls are likely to have questions of their own. For example, they may wonder when the menstrual cycle will begin and whether it will hurt.
Parents are urged to explain that no two girls experience their periods in the same way. Some begin having menstrual cycles earlier or later than others, and the menstrual cycle itself unfolds differently for each girl. Some girls have periods that last for a couple of days, whereas others experience a cycle that unfolds over the course of a week. Some girls lose just a few tablespoons of blood while others lose a half-cup or more daily. In addition, an individual girl may experience differences in her period from month to month. Parents can teach their daughter to keep a log or journal of her menstrual cycle so that predicting the next cycle is easier.
Parents are also urged to talk about the various feminine-hygiene supplies that are available, and about the need to carry these during activities such as school and social occasions. It is also helpful to explain that this new change to a girl’s body does not have to limit her in any way. Girls can continue to swim, play sports or engage in any other activities so long as they feel comfortable.
Discussing menstruation may be challenging for single fathers. Both fathers and daughters may feel uncomfortable about discussing such topics during a girl’s preteen years. In such cases, it may be helpful for a female family member to step in and explain menstruation and other such issues to the girl.
In addition, both the AAP and the American College of Obstetricians and Gynecologists recommend that adolescent girls see their primary care physician for preventive healthcare visits to discuss their reproductive health, and help establish an environment where they can feel comfortable discussing health concerns. Preventive health visits during adolescence can offer an opportunity for physicians to educate teen girls and their parents on what comprises normal puberty, menarche and the menstrual cycle.
Questions for your doctor about menstruation
Preparing questions in advance can help parents and patients have more meaningful discussions with physicians regarding their or their child’s conditions. Parents and patients may wish to ask their doctor the following questions regarding menstruation:
What are some tips for discussing menstruation with my daughter?
Should I talk about menstruation with my son, too?
I’m a single father. How can I best talk to my daughter about menstruation?
How will I know if my daughter’s first period is abnormally late?
What are some of the signs of abnormal menstruation that require medical attention?
What type of sanitary products should my daughter use for her period?
Is it okay for my daughter to use pain relievers during her menstrual cycle?
When will my daughter’s period become more regular?
How can my daughter calculate the length of her menstrual cycle?
Can my daughter get pregnant during menstruation?
If my daughter is sexually active, should she automatically see a doctor after a missed period, even if her periods tend to be irregular?
