Myths and truths about the menstrual cycle

by Tina Coleman

Remember giggling and blushing throughout your health classes as your teacher explained the menstrual cycle? Well, for many of us that class took place a long time ago. As adults we need to brush up on the basic information we were given as teens.

The basics

Suzanne Merrill-Nach, MD, a fellow of the American College of Obstetricians and Gynecologists, says that a normal menstrual cycle is one in which a woman menstruates every 28 days, with ovulation occurring approximately two weeks after the onset of a woman's last period and two weeks prior to the onset of the next.

But "normal"is a relative term, especially for teens and premenopausal women. "Almost anything can cause irregular periods," says Dr. Merrill-Nach, "including stress, illness, recently being on the Pill or using hormonal methods of birth control. Some women are simply never regular."

Dr. Merrill-Nach says a lot of women are confused about when during their cycles they can become pregnant. Trying to predict a time during your cycle when you can safely have sexual intercourse without fear of becoming pregnant can be all but impossible. "Even during ovulation," she explains, "it's risky. Although the egg lasts for only a day, sperm can last for about five days. So if you've had sex in the five days prior to ovulation, you could become pregnant."

It's also a fallacy that women cannot become pregnant if they have sex during their periods. "Say your period lasts seven days,"she says. "Sperm lasts five days. If your cycle is shorter than 28 days, you could potentially get pregnant."

The amount of flow during a woman's period will depend on the length of her cycle and whether or not she is on oral contraceptives, says Dr. Merrill-Nach. While the amount of flow is variable, she says, normally women lose less than three ounces of blood with each period.

Sex drive

For most women, the menstrual cycle and the hormones associated with it do not noticeably affect sex drive, says Merrill-Nach. Women not on hormonal methods of birth control may feel more interested in sex around the time they ovulate and some women may feel more sexy or sexual around the time of their periods, she says, but sex drive is a very individual thing. It can be affected by such variables as a date, a bad day, illness, a new baby, exhaustion, etc.

"Sex drive and interest in sex can change for numerous reasons, including hormonal fluctuations and situational stress," she says. "Your partner's interest may vary too, so it's really important to communicate."

Sex drive may be greater during menopause, she says, because women may not be worried about pregnancy, their children have left home, and they may feel more sexual. Some women, however, experience decreased sex drive after menopause.

Birth control

Dr. Merrill-Nach says she finds women are often confused about the effectiveness of the various methods of birth control. In theory, barrier methods of birth control such as the condom and diaphragm are very effective in preventing pregnancy. In reality, however, the numbers show them to be less so. This is due to the fact that they must be readily available and used correctly in order to be effective.

While the Pill is more likely to be used correctly than barrier methods, she adds, women frequently forget to take it. If you use the Pill and happen to miss a day, the information that comes with the prescription will give you directions to follow to protect yourself from unwanted pregnancy.

Toxic shock

Toxic shock syndrome (TSS) is caused by toxins released by a bacteria present in the vaginal lining. When tampons are left in place for too long, the vaginal lining can dry out, allowing these toxins to enter the blood stream. Untreated, TSS can lead to kidney failure, respiratory failure and death. Under certain circumstances diaphragms and sponges can also cause TSS.

Incidences of TSS have decreased markedly since the "really super-absorbent" tampons have been taken off the market, says Dr. Merrill-Nach, and tampons are generally quite safe and convenient. However, she stresses that it's important to change your tampon every four to six hours and to use pads instead of tampons at night.

When should you see your doctor?

Dr. Merrill-Nach recommends that healthy women see their doctors once a year for a clinical breast examination, abdominal and pelvic examinations, and a Pap smear. But should any of the following symptoms occur between scheduled checkups, see your doctor:

  • Your period comes less than 21 days or more than 35 after the onset of your last period (21 to 35 days is the normal range)
  • Your period is frequently irregular
  • Your period lasts more than one week
  • Your flow is heavier than normal
  • There is more pain associated with your period than you consider to be normal

Painful intercourse, she adds, isn't normal and should also be evaluated. Women in their forties are often quick to write off irregularities in their periods as signs of approaching menopause, says Dr. Merrill-Nach. But women approaching menopause are at increased risk of developing pre-cancerous changes, so any irregularities should be evaluated by a physician.

A woman of any age who is not having periods should be evaluated, she stresses. "Not having periods can lead to pre-cancerous changes in the uterus," she says. "It's important to find out why you're not having periods."

"If you're having predictable, regular periods until you're clearly menopausal your hormones are probably fine," Dr. Merrill-Nach explains. "If not, get yourself checked."