Jan. 31, 2006 - Maybe you grew up calling it Aunt Flo. Perhaps you referred to it as "my friend." But despite references that imply familiarity, most of us don't really know that much about our monthly menstrual periods. After having "the talk" with your mother, you probably learned little beyond what your own experiences told you.
So it might surprise you to learn that some women get a period every 11 days, and others, every 100. Some women lose so little blood every month that it's barely measurable, while others lose more than two cupfuls every cycle. Researchers have also found that most women are acutely aware of even the slightest change in their cycle, and can often accurately recall menstrual events from years before, especially if they occurred during a major life event.
Women also have a tendency to worry about these changes. Phyllis Kernoff Mansfield, a professor at Pennsylvania State University and one of the leading authorities on menstruation in the country, says that too often women assume that any change is a sign of disease, especially cancer. While it's smart to be vigilant and mention any changes in menstrual flow (like spotting between periods and very heavy flows) to your doctor, these events shouldn't inspire panic. That's because there are many more versions of "normal" menstruation than we once thought.
Discovering what's really normal has been the goal of the TREMIN Research Program on Women's Health, the oldest and longest-running study of menstruation in the world. It got its start in the botany department at the University of Minnesota in 1934 and has followed several thousand women (including generations of women in the same families) ever since, even though it is now based at Penn State. TREMIN researchers were the first to establish that every healthy woman did not have a 28-day cycle, as scientists once insisted was true. To do that, the amazingly patient founder, Dr. Alan E. Treloar, followed 2,702 women for 30 years and tabulated most of the data by hand before converting it to punch cards in the 1960s. His research also proved that cycle variability was at its most extreme at the start, when girls first started menstruating, and at the end, just before menopause. Women between the ages of 20 and 40 turned out to have the most consistent cycles.
In more recent years, TREMIN (an acroyn created by combining the first three letters of Treloar and Minnesota) has helped disprove the idea that heavy menstrual bleeding wasn't very common. It turns out that it affects about 10 million American women a year, half of them in the 40-to-50-year-old age group, and it can have a powerful impact on their lives. Mansfield, the director of TREMIN, says 40 percent of the women who regularly have heavy bleeding say they have difficulty working outside the home because their periods are so unpredictable and heavy that they live in constant fear of having a public accident. The blood loss can also put them at risk for anemia.
What exactly is an excessively heavy period? Scientists describe it as 80 milliliters or more of blood loss per cycle. That's about a third of a cup. (Average blood loss is more in the range of an eighth to a quarter of a cup of discharge a month.) Some studies indicate that in extreme cases, the loss can be more than two cups per cycle (or 500ml). But how would any one woman know how much she's losing? No one catches their monthly flow in a measuring cup.
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