The Menstrual Cycle

The Menstrual Cycle


In females the menstrual cycle is a self-regulating process during which the body undergoes many physiological and hormonal changes. The menstrual cycle is regulated by two hormones secreted from the pituitary gland, follicle stimulating hormone (FSH) and luteinizing hormone (LH). These control the production of the hormones estrogen and progesterone, which are produced in  the ovaries.

Females begin their menstrual cycle during puberty at the onset of menarche, their first menstrual period. Females continue to have many menstrual cycles throughout their lives until menopause occurs between ages 40 to 60. The average menstrual cycle lasts about 28 days, but can last anywhere from 24 to 42 days. There are three major phases of the menstrual cycle: the menstrual phase, the proliferate phase, and the secretory phase. Click here for more information on menstrual products. 


The Menstrual Phase

The menstrual phase is the phase during which the lining of the uterus, called the endometrium, is shed as menstrual flow out of the cervix and vagina. This process is what women experience during their menstrual periods, and the menstrual flow actually consists of blood, mucus, and tissue. The first day of menstrual flow is defined as day number one of the next menstrual cycle. Menstruation lasts for approximately 3 to 7 days, although some women have shorter or longer periods. Menstruation is triggered by reduced levels of the hormones estrogen and progesterone at the end of the previous menstrual cycle. The onset of a new menstrual period indicates that the woman is not pregnant. However, this does not mean that a woman cannot become pregnant during her period; women can get pregnant at any time throughout their menstrual cycle. Also during the menstrual phase, the pituitary gland begins to secrete follicle-stimulating hormone (FSH). Rising levels of FSH trigger the beginning of the next phase, called the proliferative phase.

The Proliferative (Follicular) Phase

Also referred to as the follicular phase, the proliferative phase is the part of the menstrual cycle during which follicles inside the ovaries develop and mature in preparation for ovulation. The levels of FSH increase in the bloodstream during the proliferative phase, stimulating the maturation of follicles. Each follicle contains an ovum, or egg. Although many follicles may grow and increase in size during this phase, only one will reach full growth and release the ovum at the time of ovulation.

Also during the proliferative phase, the ovaries produce estrogen. The rising levels of estrogen cause the lining of the uterus to begin thickening. (The proliferative phase gets its name from the proliferation of the cells in the uterine lining at this time.) Once the levels of estrogen are at their peak, the pituitary gland slows the secretion of FSH, and instead begins to secrete luteinizing hormone (LH). As a result of the increase in LH, the mature follicle ruptures and releases the ovum from inside. Once released from the ovary, the ovum will then travel to the fallopian tubes. The releasing of the mature egg from the follicle is called ovulation. Ovulation occurs 14 days before the beginning of the next menstrual period. Ovulation is the most fertile time during a woman's menstrual cycle.

The Secretory (Luteal) Phase

After ovulation occurs, LH causes the burst follicle to develop into a structure called the corpus luteum. The corpus luteum is a small yellow structure in the ovary that secretes the hormones estrogen and progesterone. The progesterone and the estrogen are at a high level during the secretory phase, and they help prepare the endometrium to secrete nutrients that would nourish a conceptus if a fertilized egg were to implant in it. If conception and implantation do not occur, the pituitary gland will reduce LH and FSH production. Without the presence of LH, the corpus luteum deteriorates and subsequently the estrogen and progesterone levels decrease. The drop in estrogen and progesterone levels triggers the shedding of the endometirum, causing menstruation to begin and the cycle starts over again.


Menstrual Difficulties


Starting at menarche, a girl's first menstrual period, at puberty and continuing to menopause, the cessation of menstruation, much later in a woman's life, a female will have go through the menstrual cycle many, many times. To some, this monthly phase reminds them of the gift that only women have (the ability to bear children) while others just find it an annoying bloody mess. Regardless of your personal view on this phenomenon of the female reproductive system, it can be confusing and frustrating when things go wrong. Our bodies are not without flaws, and the female reproductive system is a very fragile structure, susceptible to many problems. Besides the effects that STD's can have on the reproductive system and menstruation, there are also other problems women can have with their periods.

Premenstrual Syndrome (PMS)

PMS is not recognized as a disorder, and its existence is debated rather heavily as being either psychological or in fact physiological part of the menstrual cycle. There are so many everyday symptoms on the PMS checklist, such as lethargy, sadness, headaches, lack of interest in sex (or heightened interest in sex), etc., that even a male could be diagnosed with the syndrome it seems (Tavris, 1992). Many attribute PMS to the mind of the woman "complaining" and she should therefore "grin and bear it." It is also a societal assumption (most often in the West where fertility is not as high and more people pay attention to the signs of PMS), that whenever a woman gets moody, she must therefore be premenstrual. It is as Care Boothe Luce once wrote, "When a man can't explain a woman's actions, the first thing he thinks about is the condition of her uterus."
These kinds of attitudes discredit the actual physiological symptoms that many women experience before their period. PMS is perhaps the most common menstrual problem. It is estimated that 30 to 90% of women experience mild discomfort while premenstrual and only 5% of women experience no symptoms of PMS. Even cross-culturally, menstruation has serious emotional and psychological distress. The "symptom" list that women "suffer" from is long (over 200 items are listed), ranging from the typical (bloating, breast swelling, irritability, tension, etc.) to very adverse affects (epilepsy, lack of coordination, depression, spontaneous bruising, and many more). The culprit for all these ailments is thought to be a malfunction in the production of progesterone which disrupts the normal working of the cycle. This theory is only speculatory and researchers have found no proven cause of PMS.

Premenstrual Dysphoric Disorder (PMDD)

PMDD is much less common than PMS, and it is a recognized disorder that can be diagnosed. Only 5% of women have severe enough symptoms for the PMDD diagnosis, and a woman is not diagnosed unless her daily functioning is impaired. The disorder PMDD, while it has physical symptoms, is considered a distinct type of depressive disorder and is applied to a woman only when she repeatedly has 5 of 11 symptoms during the week before her period: 1) sad or hopeless feelings 2) tense or anxious feelings 3) marked mood changes 4) frequent irritability or anger and increased interpersonal conflicts 5) decreased interest in her usual activities 6) lack of concentration 7) lack of energy 8) lack of appetite 9) insomnia or sleepiness 10) a subjective feeling of being overwhelmed or out of control 11) physical symptoms such as swollen breasts, headaches, muscles pain, a "bloated" sensation, or weight gain. Just like PMS, the exact cause of PMDD is not known.


Amenorrhea, the absence of menstruation, is actually a quite common problem for women. There are two basic types of amenorrhea, primary, when a girl fails to menstruate at puberty, and secondary (which is the more common type), the disruption of an established menstrual cycle with the lack of menstruation for 3 or more months. Primary amenorrhea is caused by a variety of factors, like hormonal imbalance, poor health, or a problem with reproductive organs. Secondary amenorrhea is actually a normal condition during and after pregnancy (postpartum amenorrhea) and during breast-feeding (lactational amenorrhea). Secondary amenorrhea is also common for women who just started menstruating or are nearing menopause. Sometimes secondary amenorrhea is referred to as pathological amenorrhea because it signifies a pathological absence of menstruation and is unrelated to the normal conditions previously mentioned.
There are many factors associated with the absence of menstruation. Age is huge indicator in the regularity of a woman's cycle. The greatest menstrual variations among women have been found in the groups before age 19 and between 40 and 50 years of age (Collet, Wertenberger, Fiske, 1954). "The probability of a cycle being defective in any way is greatest during the years following menarche and rises again during the 5 years preceding menopause." Also very important to a woman's reproductive health is nutrition. Extreme malnutrition, either self inflicted by eating disorders or as a result of environment such as famine, can produce temporary amenorrhea. Once energy intake increases, the female body has a remarkable potential to recover from the damages of malnutrition. There is a potential for some repercussions later, such as spontaneous abortions, difficult birthing process, longer postpartum amenorrhea, and subfecundity.
In addition, disease can also chase away a woman's period. Some of the non-sexually transmitted diseases that can cease menstruation are tuberculosis, filariasis, schistosomiasis (Charlewood, 1956), Gambian sleeping sickness (WHO, 1979), mental illness such as schizophrenia and manic-depressive psychoses (Shader, Nahum, DiMascio, 1970), and even diabetes (Gold, 1968). As well, a woman's psychological state has a great deal to do with her menstruation cycle. Stress and fear are the two major causes that make a woman's period go missing (Coldsmith, 1979). Varying levels of psychological disturbance, ranging from trauma from after a rape to chronic stress to relatively minor stresses like from exams, can lead to a disturbance in a woman's cycle. In addition, some research shows that amenorrhea could be due to "a desire to avoid the adult female sexual role and pregnancy" (Jacobs, 1972). The last important factor related to secondary amenorrhea is physical activity. Often the female body has an adaptive mechanism that turns of menstruation under strenuous physical conditions, which is a common occurrence for female athletes. Athletic amenorrhea is connected to rigorous activity, emotional stress of competition, weight loss, and low estrogen levels (Cuming, 1993).
Usually women's main concern with amenorrhea is their fear of being unable to conceive. Amenorrhea does not directly correlate with sterility. It does however have an affect on fertility, but research has yet to fully explain this relationship.


It is speculated that women have a higher tolerance for pain than men because they are responsible for giving birth to future generations, which is a most taxing experience on the female body. Even with a greater tolerance for pain, many women find their periods to be a quite agonizing ordeal. Painful menstruation is called dysmenorrhea. There are two basic types of dysmenorrheal, primary and secondary. The main difference between the two is their cause. Primary dysmenorrhea is caused by the over production of prostaglandins, a hormone that causes the muscles of the uterus to contract. Symptoms include abdominal cramping, nausea, vomiting, diarrhea, headache, dizziness, fatigue, and irritability. Secondary dysmenorrhea is caused by a variety of factors, such as presence of an IUDPID, uterine tumors, obstruction of the cervical opening, or endometriosis (a condition where uterine tissue grows on various parts of the abdominal cavity). Prior and during menstruation, secondary dymenorrhea has a wide range of symptoms: constant (almost spastic) lower abdominal pain, pain in back and thighs, and painful intercourse.

Help for Menstrual Problems

What if you have menstrual problems? While it may seem that your body has a mind of its own, there are some things that you can do to help alleviate the unpleasantness of periods. Moderate exercise and proper exercise help both body and mind. Cutting back on salty foods helps with water retention and bloating, and many vitamins and minerals often help with cramping. It is a good idea to keep written record of your periods; this way you can track the symptoms, length of cycles, stresses, etc. You may be able to find a pattern between menstrual difficulties and aspects of your own life. For example, you might find, as many women do, that exercise throughout the month helps with the pains of periods.

If your menstrual cycle is causing you great discomfort it might be a good idea to see a doctor. Prescription drugs and over-the-counter medications are available to help alleviate menstrual pain and regulate cycles. Depending on the diagnosis your doctor gives you, there should be a variety of treatment options open to you. So although the topic may be embarrassing and somewhat uncomfortable to talk about, it is worth your while to consult your doctor.



Spotting occurs when the uterus sheds blood intermittently between periods. Alternative names for spotting include: abnormal uterine bleeding, bleeding between periods, intermenstrual bleeding, and metrorrhagia. Many women who experience spotting can be alarmed.

Normal menstrual bleeding lasts anywhere from 2 to 7 days, produces a total blood loss of 30 to 80 ml (about 2 to 8 tablespoons), and recurs normally every 28 days (+/- 7 days).

If a woman is experiencing spotting, she should first make certain that the bleeding is coming from the vagina (and not from the rectum or in the urine) so that she may properly understand the situation and relay accurate information to a doctor if necessary. A good way to check if the bleeding is coming from the uterus is to insert a clean tampon, remove it, and inspect it for any traces of blood. It is important not to douche in an effort to clean the vagina and rid it of blood or discharge. Spotting is a natural process and should be left to run its course or be evaluated by a physician.

Spotting may occur for a variety of reasons, including but not limited to: stress, changes in hormone levels (which may be linked to hormonal birth control use), IUD use, poor diet, excessive exercise, or lack of proper lubrication during sex. Inadequate lubrication can cause small tears inside the vagina that lead to bleeding. This problem can easily be remedied by using a lubricant, such as KY Jelly or Astroglide. Some females experience spotting for a few days before or after their period, which is considered normal. Usually spotting stops once the problem is fixed, or it may stop naturally after a time.

Spotting is normal during the first month or two of starting hormonal birth control pills or when switching birth control methods. When a woman has an IUD inserted, cramping and spotting are also common.

If spotting becomes incessant, painful, or problematic, you should consult a physician who can ascertain the cause of the bleeding through a careful exam. It is essential to know that a doctor can best give an evaluation while the bleeding is occurring, so it is important not to wait until the bleeding stops. In order to keep track of how much bleeding is occurring, a woman can count the number of pads and/or tampons used to control the bleeding. This is important information to share with her physician if the bleeding becomes heavy, painful, or problematic. You should see a doctor to find out whether or not your spotting is the sign of a larger problem.


Problematic occurrences for vaginal spotting are:

  • Ectopic Pregnancy.
  • Low Thyroid Function.
  • Injury or disease to the vaginal opening caused by intercourse, infection, uterine fibroids/polyps, genital warts, ulcers, varicose veins, insertion of foreign objects, or malignancy.
  • Cervical Conization or cauterization procedures.
  • Drugs such as anticoagulants.

The following individuals should contact their physician at first notice of the bleeding: women who are pregnant, women who experience bleeding after menopause, or if the bleeding is accompanied by other unusual symptoms. Any vaginal bleeding may be something to worry about for women who are postmenopausal (generally women over the age of 50), since the risk of malignancy increases steadily with age.

At a young age, and especially for the first few years after menarche, it is normal for menstruation to still be fluctuating. Sometimes the distinction between spotting and a "light period" may be unclear. A light period is not as heavy as your normal period but still requires you to change your regular pads or tampons a few times during the day. Spotting would be wearing light tampons or pantyliners and having to change them only a couple times during the day.

If a woman is experiencing pain along with spotting, she should refrain from taking aspirin, because it acts as a blood thinner. Instead, she should contact her physician for immediate care.



Crooks, R., & Baur, K. (2005). Our sexuality. Belmont, CA: Thompson Wadsworth.

Hyde, J.S., & DeLamater, J.D. (2006). Understanding human sexuality. New York: McGraw-Hill.

Menstrual cycle. (n.d.). Retrived February 12, 2007, from