5 Things You Didn't Know About Your Period

or for decades -- and you think
you're in the know. Then up pops a question from you or one of your friends
that no one can answer with certainty.  That doesn't surprise
gynecologists, who say they often field menstrual cycle questions from their patients.

Here, three top gynecologists talk about the most common questions they get
about periods and what they tell their patients.

1. Why do I get PMS?

PMS ,
or premenstrual syndrome, occurs because your body is sensitive to hormonal
changes, says Richard P. Frieder, MD, a staff gynecologist at Santa Monica
UCLA & Orthopaedic Hospital in Santa Monica, Calif. "In the week or 10
days before your period comes, hormone levels -- progesterone and estrogen --
are changing rapidly," he says.

That can cause symptoms such as bloating , mood swings, headache , breast tenderness, and fatigue in some women, he says.

As many as 90% of women experience some symptoms before their period,
according to a study in the Archives of Internal Medicine, but many
fewer -- 20% or less -- have symptoms severe enough to interfere with normal
activities and relationships and be termed PMS.

Whether you have just a few mild symptoms or full-blown PMS, Frieder
advises: "Make your body as healthy as possible. Try to get exercise
every day, especially on the day you get PMS. Drink lots of water so you are
not dehydrated. Eat every couple of hours. Stay away from alcohol and
caffeine."

From there, he believes in treating individual symptoms. If moodiness is a
problem, for instance, he sometimes prescribes calcium supplements .

A high intake of calcium and vitamin D seems to reduce the risk of getting
PMS, according to a study that followed more than 3,000 women and was published
in 2005 in the Archives of Internal Medicine. Women who ate about four
servings a day of low-fat milk or dairy foods or fortified orange juice were
less likely than those who didn't to develop PMS over the 10-year
follow-up.

Some experts have suggested that vitamin D and calcium deficiencies lead to
the PMS.

Often, women with more severe premenstrual symptoms report amazing relief
when they go on birth
control pills , says Frieder, who is also an assistant clinical professor of
obstetrics and gynecology at the University of California Los Angeles David
Geffen School of Medicine. Low doses of antidepressants are sometimes prescribed to improve the
mood swings.

2. Why are my cycles irregular?

Some women don't ovulate regularly and therefore have irregular periods,
Frieder says. Stress and illness, for
instance, can adversely affect the cycle.

But it's important to know the definition of a "regular" cycle
before deciding you are having irregular periods, Frieder says. What some women
think is an irregular cycle may not be, he says. A "regular" cycle,
Frieder says, means one that is between 25 and 35 days -- counting from the
first day of bleeding to the start of your next period.

"Many women consider themselves not normal if they don't get their
period on the same day of the month, every month," says Mary S. Dolan, MD,
MPH, associate professor of obstetrics and gynecology at Emory University
School of Medicine, Atlanta. She tells them not to worry and not to expect it
the exact same day of the month.

Sometimes women's memory about when their last period was is not accurate,
she says. For that reason, she suggests her patients keep a menstrual calendar
or other record, making note each month of when their period starts and
stops.

Other reasons for irregular or missed periods (besides pregnancy ) include excessive
weight gain or loss, eating disorders, strenuous exercise such as that done
by endurance athletes, and hormonal problems.

If your period doesn't return to normal the next month, you can check in
with your doctor.

3. Is it possible to get prenant during my period?

Possible, but not likely, experts concur. The key is to determine if the
bleeding is really a period, says Dolan. It may just be spotting between periods.  "Some women have
bleeding when they are ovulating ,'' Dolan says.
"And if you interpret that as a period, yes, you can get pregnant."

Or a woman may have intercourse toward the end of her period and, depending
on the length of her cycle, ovulate a few days later. "You could
technically be at the end of your period, ovulate two or three days later, and
the sperm is still there," Dolan says. And you could get pregnant. Not
likely, but possible.

4. If I get my period, can I be sure I am not pregnant?

You can't be 100% sure, says Dolan. "It could be bleeding in early
pregnancy," she says. "You can't always tell the difference." 
Pay attention to whether it progresses as a regular period.

She advises women: If you have other symptoms such as nausea , check with your doctor. A pregnancy test might be wise.

5. If I leave in a tampon too long, am I at risk for toxic shock syndrome?

Toxic shock syndrome, or TSS, a life-threatening illness caused from a
bacterial infection, made headlines in 1980 when an outbreak occurred that
mostly involved young women who had been using a specific brand of very
absorbent tampons (the brand is now off the market.) The bacteria produce
toxins that cause toxic shock syndrome.

TSS is marked by a sudden onset of fever , chills, diarrhea , vomiting, muscle aches, and rash . Some experts say that very absorbent tampons,
when left in place for a long time, become a breeding ground for bacteria and
cause the syndrome. Others say how long you leave in a tampon doesn't increase
your risk of getting sick. 

Ideally, how long should you leave in a tampon? "Follow what the package
insert says,'' suggests Deidre Defoe, MD, clinical director of Rachel's Well, a
nonprofit women's health care organization based in Virginia.

On the web site of one popular tampon brand, for instance, it recommends
changing the tampon at least every four to eight hours.

Know that the condition is rare. In the U.S., about one or two of every
100,000 women ages 15 to 44 get toxic shock syndrome annually, according to the
CDC.

Many experts say they have never seen a case since they have been in
practice. "Toxic shock is something everyone learns about in medical
school," Defoe says. But Defoe says she has yet to see a case.

By Kathleen Doheny
Reviewed by Louise Chang
©2005-2006 WebMD, Inc. All rights reserved