Six Things Every Woman Should Know About Her Periods Before Menopause

When to worry, when to go with the flow
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It seems like only yesterday you were snickering in health class as you learned about feminine hygiene and your impending first period. Now here you are in the prime of life -- and it's already time to think about your last.

By your 40s -- and sometimes earlier, for the 1 to 5 percent of women headed for premature menopause -- important menstrual-cycle changes are already on the way. Here's what to know.

A skipped or heavy period might be your first sign of menopause.

Your menstrual cycle until menopause isn't a now-you-see-it, suddenly-you-won't kind of thing. "The ovary doesn't stop, boom!" says Sandra Carson, a professor of ob-gyn at Brown University and medical director of the Center for Reproduction and Infertility at Women's and Infants Hospital of Rhode Island.

Most women experience gradual menstrual irregularity during the phase known as perimenopause, the three to five years before menopause. Estrogen levels start falling even earlier, as eggs disappear from the ovaries, though we don't notice. Ongoing hormonal shifts finally become obvious in the form of changing periods.

Usually this means lighter and less frequent, but "normal" reactions are surprisingly variable. A woman's periods may turn longer than usual, shorter than usual, space farther apart, or in some months be skipped entirely. Some women begin to have bouts of heavy bleeding. Others spot between periods.

Tracking their timing, length, and nature now can help you notice the changes.

Bleeding changes are normal, but you shouldn't assume they're normal.

Even though the majority of women develop some kind of menstrual irregularity in their 40s as the body closes shop on reproduction, heavy bleeding is one symptom you should always report to your doctor.

At minimum, heavy periods can lead to anemia or disrupt your ability to conduct daily life. (Example: a teacher or a surgeon who must spend hours on her feet without a break.) But heavy bleeding can also flag other treatable conditions that can affect women of any age, including fibroids, polyps, ovarian cysts, an overgrowth of the endometrium (uterine lining), or, rarely, uterine cancer.

"Heavy" periods can feel different from woman to woman.

The medical definition of a heavy period (menorrhagia) is more than 80 ccs (cubic centimeters) of blood, or about three ounces, according to Carson. (Most women lose about six teaspoons of blood per cycle.) But who measures her flow, let alone knows what 80 ccs looks like? And if you're someone who's always had intense periods, what should you look for?

Trust what seems like a change for you. "After you've been menstruating for 30 years, you know when there's a change," Carson says.

Also look for: clotting, using more than one high-absorbency pad at a time, combining a tampon plus a pad, needing to change pads hourly, bleeding steadily for more than seven days. The American College of Obstetrics and Gynecologists also recommends telling your doctor if you're bleeding more often than every three weeks or you bleed after having sex.

More things every woman should know about her periods before menopause

There's no link between menstrual difficulty in your reproductive years and menstrual difficulty in perimenopause.

Good news for women plagued by heavy bleeding, cramping, and bad PMS (dysmenorrhea): Your odds of a rough passage through menopause seem to be about the same as any woman's, says Carson. But there's some evidence that stress worsens both PMS and perimenopausal symptoms.

You can still get pregnant even after you start missing periods.

The number-one mistake women with menstrual irregularity make (after not checking with a doctor about big changes): assuming that being down the road toward menopause means you can't conceive -- or that your odds are so low it's not worth bothering about.

"Your chances of pregnancy are low and your chances of miscarriage are high once your periods become irregular in perimenopause, but you can still get pregnant," says Carson, an ob-gyn and endocrinologist. And every year, thousands of perimenopausal women do.

Some doctors keep healthy women without risk factors (like smoking) on hormonal contraceptives through their early 50s, since that has the same protective effects against menopausal symptoms (such as minimizing abnormal bleeding or hot flashes) as hormone replacement therapy (HRT). Others prefer to transition patients to HRT or alternatives, along with an alternate birth control method. Some advise women to wean off hormonal contraceptives by their late 40s in order to measure levels of FSH (follicle-stimulating hormone), which, when elevated, indicate that the ovaries are failing and heading toward menopause. To get an accurate reading, a woman should not be taking hormonal contraceptives for as long as six weeks before testing.

Women in their 40s who have quit birth control pills may be advised to wait 18 months without a period before considering another form of contraception unnecessary. Another reason to consider contraceptives in perimenopause and beyond: You'll still need protection against sexually-transmitted diseases if you're sexually active and not in a long-term monogamous relationship.

You won't know your last period when you see it.

For such a big deal, the official end of tampons, pads, and birth control always slips by without notice. "There's no test to say you'll go into natural menopause next month or next year," Carson says. "Some tests [such as blood tests to measure FSH] will suggest it will probably occur in the next three to five years, but that's the best we can do."

The average age of menopause is 51, most often occurring between 45 and 55. The extreme -- and rare -- ends of "normal" are the early 40s and as late as 60.

"Menopause itself is defined as the last menstrual period, but you won't know when that was until one year afterward," says Carson. That's because technically, menopause isn't the whole passage commonly referred to, from menstrual irregularity through hot flashes. It's the day menstruation ends -- as noted only by looking back on 12 full months without menstruation. Period.

Paula Spencer Scott

Paula Spencer Scott is the author of Surviving Alzheimer's: Practical Tips and Soul-Saving Wisdom for Caregivers and much of the Alzheimer's and caregiving content on Caring. See full bio