Teens: Menstrual Cycle : Part 3

by Food and Drug Administration (FDA)

(Page 3 of 3)

Monthly Changes

Menstruation is just one part of the menstrual cycle, in which a woman's body prepares for pregnancy each month. A cycle is counted from the first day of one period to the first day of the next. An average cycle is 28 days, but anywhere from 23 to 35 days is normal.

Estrogen and progesterone levels are very low at the beginning of the cycle. During menstruation, levels of estrogen, made by the ovaries, start to rise and make the lining of the uterus grow and thicken. In the meantime, an egg (ovum) in one of the ovaries starts to mature. It is encased in a sac called the Graafian follicle, which continues to produce estrogen as the egg grows.

At about day 14 of a typical 28-day cycle, the sac bursts and the egg leaves the ovary, traveling through one of the fallopian tubes to the uterus. The release of the egg from the ovary is called ovulation. Some women know when they're ovulating, because at mid-cycle they have some pain — typically a dull ache on either side of the lower abdomen lasting a few hours. The medical word for this is mittelschmerz, from the German, meaning middle pain. Some women also have very light bleeding, or spotting, during ovulation.

After the egg is expelled, the sac — now called a corpus luteum — remains in the ovary, where it starts producing mainly progesterone. The rising levels of both estrogen and progesterone help build up the uterine lining to prepare for pregnancy.

The few days before, during and after ovulation are a woman's "fertile period"-the time when she can become pregnant. Because the length of menstrual cycles vary, many woman ovulate earlier or later than day 14. It's even possible for a woman to ovulate while she still has her period if that month's cycle is very short. (Stress and other things can sometimes cause a cycle to be shorter or longer.) If a woman has sex with a man during this time and conception occurs (his sperm fertilizes the egg), she becomes pregnant.

The fertilized egg attaches to the uterus, and the corpus luteum makes all the progesterone needed to keep it implanted and growing until a placenta (an organ connecting the fetus to the mother) develops. The placenta then makes hormones and provides nourishment from the mother to the baby.

If an egg is not fertilized that month and the woman doesn't get pregnant, the corpus luteum stops making hormones and gets reabsorbed in the ovary. Hormone levels drop again, the lining of the uterus breaks down, menstruation begins, and the cycle repeats.

In the illustration below, an egg has left an ovary after ovulation and is on its way through a fallopian tube to the uterus.

Menstrual Bleeding: What's Normal, What's Not

Most menstrual periods last from three to five days, but anywhere from two to seven days is normal. The amount of blood flow varies, too, but for most women, bleeding starts out light at first, followed by heavier flow for a day or two and then another light day or two. Sanitary pads or tampons, which are made of cotton or another absorbent material, are worn to absorb the blood flow. Sanitary pads are placed inside the panties; tampons are inserted into the vagina.

"The amount of bleeding varies from woman to woman because everybody's body has a different way of building up the lining of the uterus," says Lisa Rarick, M.D. "A lighter flow or heavier flow doesn't mean you can't get pregnant as easily or you're never going to get pregnant, or that your periods will always stay the same way. But if you're bleeding excessively-soaking one or more tampons or pads an hour-you should see a doctor to see if there's a problem."

Rarick, a gynecologist with FDA's Center for Drug Evaluation and Research, says teenagers often are concerned if they expel blood clots during their periods. She says this is not dangerous; they are clumps of pooled blood in the vagina. Sometimes, instead of flowing freely, blood drains from the uterus and stays in the vagina until there's a change in position — say, from sitting to standing.

Women who use tampons should be aware of toxic shock syndrome, or TSS, a rare but serious-and sometimes fatal-disease that's been associated with tampon use. Tampon packages carry information about TSS on the box or inside. Because TSS mostly affects 15- to 19-year-olds, it's especially important for teenagers to know what signs to look for. If you develop the following symptoms while menstruating, remove the tampon and get medical help right away:

• sudden fever over 102 degrees Fahrenheit
• vomiting
• diarrhea
• dizziness, fainting, or near fainting when standing up
• a rash that looks like a sunburn.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.