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A Balanced Look at the Menstrual Cycle

A Balanced Look at the Menstrual Cycle

woman holding a period calendar tracker

Some young women feel it coming days before they get it. Others are hardly aware they have it. Friends who compare notes about their periods will probably find that menstruation — the monthly shedding of the lining of the uterus, or womb-affects each of them a little differently, both physically and emotionally.

“The menstrual cycle has its ups and downs of hormones, and different people react differently to hormonal swings,” says Lisa Rarick, M.D., a gynecologist in FDA’s Center for Drug Evaluation and Research. She explains that just before and during menstruation, levels of the female hormones estrogen and progesterone are low. That’s when some women feel bloated, irritable or blue, or “just crummy,” she says.

“Just crummy” might mean cramps, sore breasts, backache, headache, nausea, and feeling tired.

“A day or two after your period starts you begin to feel better. Hormone levels go back on the upswing and you get back to what you’re accustomed to during the rest of your cycle,” Rarick explains. (See “Monthly Changes.”)

Cramps: A Common Complaint

More than half of menstruating women have cramp-like pain during their periods. The medical term for menstrual pain is dysmenorrhea. Cramps are usually felt in the pelvic area and lower abdomen, but can radiate to the lower back or down the legs.

“Many girls have cramps severe enough to keep them home from school,” Rarick says. In fact, according to Danforth’s Obstetrics and Gynecology, dysmenorrhea is the most frequent cause of absenteeism from school among younger women. Rarick says women seem to go through phases when cramps are severe, then get better for several years, and then maybe worsen again. She adds that most women find they have less menstrual pain after having children.

Mechanically, cramps are like labor pains. Just as the uterus contracts to open up the cervix (neck of the uterus) and push out a baby, it contracts to expel menstrual blood. Often, after several years of menstruating or after childbirth, the cervical opening enlarges. The uterus doesn’t have to contract as much to discharge the menstrual flow, so there is less cramping.

Menstrual pain may also come from the bleeding process itself. When the uterine lining separates from the wall, it releases chemicals called prostaglandins. Prostaglandins cause blood vessels to narrow, impeding the supply of oxygen to the uterus. Just as the pain of a heart attack comes from insufficient blood to the muscles of the heart, too little blood to the uterine muscle might cause the pain of menstrual cramps.

Menstrual pain can have other causes, although these are rare among teenagers. They include tumors, fallopian tube infection, and endometriosis, a condition in which fragments of the lining of the uterus become embedded elsewhere in the body.

Pain, Pain Go Away

Sometimes, simple measures are all that’s needed to feel better. Cutting down on salt might help reduce fluid buildup, and support hose may alleviate swelling in the legs or ankles. Crawling into bed for some extra rest or sleep is one way to deal with fatigue, and taking along a heating pad or hot water bottle eases cramps for some. Exercising also helps reduce pain in many young women, and may lift a blue mood as well.

Charles Debrovner, M.D., associate clinical professor of obstetrics and gynecology at New York University School of Medicine, explains that exercising during menstruation lessens pain because it causes release of brain chemicals called endorphins, which are natural painkillers. He says exercise may also decrease pain by affecting prostaglandin metabolism.

Rarick adds that exercise may also help because it increases blood flow, and because it “just makes a lot of people feel better in general.”

If symptoms interfere with work, school or sleep, the American College of Obstetricians and Gynecologists recommends seeing a doctor, who may suggest taking one or more medicines. Certain anti-inflammatory drugs called NSAIDs (an abbreviation for nonsteroidal anti-inflammatory drugs) inhibit prostaglandin production, thus easing cramps. Prescription NSAIDs include naproxen (Naprosyn, Anaprox), ibuprofen (Motrin, IBU), indomethacin (Indocin), and mefenamic acid (Ponstel).

If needed, your doctor may prescribe stronger painkillers or diuretics, or even oral contraceptives. One side effect of birth control pills is relief of menstrual cramps.

“Birth control pills work two ways to lessen cramps,” says Rarick. “They prevent the lining of the uterus from building up so much, so there’s less bleeding. This means less prostaglandin production and blood vessel narrowing because there’s less lining to separate, and fewer contractions because there’s less tissue to push out.”

Over-the-Counter Relief

In 1984, FDA approved ibuprofen in over-the-counter (OTC) strengths to be sold without a prescription. It’s the active ingredient in medicines such as Advil, Nuprin and Motrin IB. In 1994, the agency approved naproxen for OTC marketing in lower doses than the prescription strength. OTC naproxen is sold under the brand name Aleve.

Like NSAIDs, aspirin also suppresses prostaglandins, but it’s often not as effective as other NSAIDs for menstrual pain. Aspirin should never be used by children or teenagers who have chickenpox or flu symptoms before checking with a doctor. This is because Reye syndrome, a rare but sometimes deadly illness, may develop in children and teenagers who have taken aspirin or products that contain it while they were sick with chickenpox or flu.

Several OTC products, such as Midol and Pamprin, are specifically formulated for menstrual symptoms. Read the labels of these medicines before you buy them, because different formulations often contain different ingredients or strengths of ingredients. For example, Teen Formula Midol contains acetaminophen for pain and pamabrom (a mild diuretic) for fluid retention. Pamprin contains acetaminophen, pamabrom and pyrilamine maleate (an antihistamine) for tension and irritability. Cramp Relief Formula Midol IB contains as its sole ingredient ibuprofen. Manufacturers may change their products’ ingredients from time to time, so it’s a good idea to check the label each time you buy the product. Plain acetaminophen products like Tylenol, Datril, and Aspirin-Free Anacin also may help menstrual pain. It takes time for pain relievers to work, so it’s best to take them before the pain gets bad and continue for one or two days, as needed.

Some 20 to 40 percent of menstruating women have PMS, or premenstrual syndrome. Starting anywhere from mid-cycle to a few days before menstruation begins, women with PMS may have one or all of a virtual laundry list of physical and emotional symptoms. They include breast swelling and tenderness, fluid retention, increased thirst or appetite, craving for sweets and salty foods, headaches, anxiety, restlessness, irritability, depression, hostility, and loss of self confidence. Experts say PMS doesn’t usually affect teenagers, though. It increases with age and is more prevalent in the 30s and 40s.

From Menarche to Menopause

In the United States, the average age of menarche — a girl’s first period-is 12 years, although it’s normal to start as early as 10 or as late as 16. Menopause–when periods stop-usually occurs around age 50, although that, too, can vary by several years. Except perhaps for the first two years of menstruation-and barring pregnancy, nursing, and certain illnesses or other problems-the reproductive cycle repeats with predictable regularity every month.

Exercise, diet and stress can delay the onset of menstruation, Rarick says, or alter cycles once they’ve been established.

“Gymnasts, ballerinas and others who exercise strenuously can sometimes delay the onset of their periods, so you might not be surprised to find a 16- or 17-year-old in that group who hasn’t started menstruating,” she says. “Some experts believe the connection between exercise and amenorrhea [the absence of menstrual periods] is related to body fat content, because fat affects estrogen. Young women who are very thin from malnourishment may not start menstruating until they gain weight, with a certain portion of that weight being fat. So, girls who exercise a lot-who are all bone and muscle with no fat-may delay their periods.”

Similarly, young women with severe eating disorders such as anorexia or bulimia often do not menstruate.

The American College of Obstetricians and Gynecologists recommends that a girl see her doctor if she hasn’t started menstruating by age 16, or if by age 13 or 14 she hasn’t begun to develop breasts or pubic and underarm hair.

Just Like Clockwork?

Many young women have very irregular periods the first couple years of menstruating — even skipping some months, until, as Rarick says, “the system is well-tuned.”

In addition, she says, young women don’t always ovulate every month when they first get their periods. She adds that there’s no sure way for a young woman to know which month she is ovulating and which she is not. So, from the time her periods begin, a young woman should assume she can get pregnant each and every month, even if her periods are irregular.

Eventually, periods become regular, but even when they do, a missed or late period once a year — especially at a stressful time — is considered normal, according to Rarick.

Also, just as strenuous exercise and eating disorders can delay the onset of menstruation, they can also cause previously regular menstrual cycles to become irregular or stop completely.

Food and Drug Administration
U. S. Food and Drug Administration Center for Food Safety and Applied Nutrition