I recently posted an article on the relationship between a paleo diet and menstrual cramps (also find more info on this relationship in my book here), but it is important to understand what menstrual cramping is in and of itself.  What are menstrual cramps, and where do they come from?  Why are they so painful, and why do so many women suffer them?

Who has menstrual cramps

Menstrual cramps of some degree affect more than an estimated fifty percent of women.  Among these, up to fifteen per cent describe their menstrual cramps as severe.  Over ninety percent of  adolescent girls today report having menstrual cramps.

Cramps are their worst in a woman’s younger years and almost always peter out into her thirties.   This is evidenced by the fact that painful menstruation is the leading cause of lost time from school and work among women in their teens and 20s.

The two kinds of cramping

In primary dysmenorrhea, there is no underlying gynecologic problem causing the pain. It is marked by abdominal pain first and foremost, but abdominal discomfort, irregular digestion, nausea, back pain, and headaches often accompany it, too.  Cramping may begin a day or two before menstruation, and it endures for the first few days of bleeding.  Menstrual cramping is commonly conflated with PMS, but they are in fact two separate medical phenomena.

In each woman, primary menstrual cramping may begin as early as six months to a year following menarche (the beginning of menstruation).  However, menstrual cramps typically do not begin until ovulatory menstrual cycles occur, and ovulation normally does not beginning happening for some time after menarche.  For this reason, an adolescent girl may not experience dysmenorrhea until months to years following the onset of menstruation.

Some women experience cramping at different periods of their lives.  Modern medicine does not sufficiently recognize this phenomena or investigate it’s causes, but periodic cramping is probably induced by dietary, stress, and lifestyle fluctuations.

In secondary dysmenorrhea, on the other hand, some underlying abnormal condition contributes to the menstrual pain. Secondary dysmenorrhea can result from endometriosis, uterine fibroids, adenomyosis, ovarian cysts, having a copper IUD, pelvic inflammatory disease, PMS, or sometimes even STIs.

What causes menstrual cramps?

The origin of menstrual cramping is in the physiological changes that take place each month in the menstrual cycle.  Each month, the inner lining of the uterus (the endometrium) builds up in preparation for a possible pregnancy.   This occurs in the first two weeks of the cycle, and is called the follicular phase.

At the start of week three, the woman ovulates.  After ovulation, if the egg is not fertilized, no pregnancy will result and the current lining of the uterus becomes superfluous. The woman’s estrogen and progesterone hormone levels thus decline, and the lining of the uterus swells.  It is eventually shed in the form of menstrual flow, and it is replaced by a new lining in the next monthly cycle.


When the old uterine lining begins to break down, inflammatory mediators called prostaglandins are released. Prostaglandins regulate muscle contraction and cause the muscles of the uterus to contract. When the uterine muscles contract, they constrict the blood supply to the endometrium. This contraction blocks the delivery of oxygen to the tissue of the endometrium which, in turn, breaks down and dies.   This occurs on the first day of menstruation.

After the death of this tissue, the uterine contractions literally squeeze the old endometrial tissue through the cervix and out of the body by way of the vagina.  This is why women who use diva cups often discern physical tissue with their menstrual discharge.  It is in fact the dead tissue of the old endometrium.

Why are cramps so painful?

Menstrual cramps are caused by the uterine contractions that occur in response to prostaglandins and other chemicals. The cramping sensation is intensified when clots or pieces of bloody tissue from the lining of the uterus pass through the cervix, especially if a woman’s cervical canal is narrow.

The difference between menstrual cramps that are more painful and those that are less painful is a direct correlation with a woman’s prostaglandin levels. Women with menstrual cramps have elevated levels of prostaglandins in the endometrium (uterine lining) when compared with women who do not experience cramps. Menstrual cramps are actually quite similar to those a pregnant woman experiences when she is given prostaglandin as a medication to induce labor.

In a normal-functioning woman, menstrual cramps occur at a given pressure and frequency.   The pressure is between 50 and 80 mmHg, they last around twenty seconds, and the frequency is ~1-4 contractions per ten minutes.  In women who experience painful cramping, this pressure can rise to 400 mmHg, and the contractions might last up to ninety seconds.

Prostaglandin activity in menstruation

Prostaglandins are eicosanoids, a class of molecules involved in the signalling of inflammation.   Specifically, prostaglandins are lipids involved in chemical signalling, but they are not endocrine hormones.  Endocrine hormones are produced from a discrete location and then sent out to the rest of the body.  Prostaglandins instead exhibit paracrine function, which means that they are produced locally and for local use all throughout the body.

In menstrual cramps,  therefore, prostaglandins are produced out of essential fatty acids in cells surrounding the uterine tissue.   Then they signal to surrounding muscle tissues to contract.  If prostaglandins are produced in excess, then the abdominal muscles receive a signal to contract that’s excessively strong, and the contractions will become strong enough for it to be painful.  Prostaglandins also affect intestinal tissue, which is why many women experience diarrhea, constipation, or changed bowel movements during the first days of menstruation.

Conventional  cramping treatment

Health professionals sometimes make holistic recommendations.  Unfortunately, they’re either obvious or ineffective, so they don’t do much for women who suffer cramping.  For example, women are told to lose weight and to quit smoking.  (Duh.)  They are also told to eat a “healthy diet” full of fruit, vegetables, and plenty of fiber, “which is particularly useful since it cleanses the body of excess estrogen (which can lead to heavier and more painful periods and cramps.”    Some doctors also recommend sleep and exercise, which are two recommendations I actually recommend myself.

More typical reactions to cramping involve the medical cabinet.  For mild cramps women are advised to take aspirin or acetaminophen.  When acetaminophen is coupled with a diruetic, such as in diurex, midol, or pamprin, it is supposed to be more effective, possibly because it accelerates the removal of prostagalandins.

For more severe cramps, women are told to take NSAIDs.  NSAIDs lower the production of prostalglandin.  Ibuprofen, naproxen, and ketoprofen are all NSAIDs that do not require prescritpions.  NSAIDs that doctors proscribe with a prescription are mefenamic acid and meclofenamate.

The final recourse for particularly painful cramping is birth control.  Birth control pills, in preventing ovulation and the regular cycling of estrogen and progesterone levels, sometimes prevents menstruation wholesale.  When women still have a monthly period, the prostalglandin levels are typically normalized and the menstrual flow lightens.

It goes without saying that these options treat the symptom, but not the cause of menstrual cramps.  Without paying attention to what dietary and lifestyle factors are affecting inflammation, pain, prostalglandin and hormone imbalances, cramps will never go away.

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What causes menstrual cramps? And why do nearly half of women suffer from them?

For additional information see my post on the paleo diet and menstrual cramps or my book, Sexy By Nature.

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