What if you had breast cancer and discovered that timing surgery to coincide with a particular point in the menstrual cycle might make a difference in your prognosis?
Or what if you had diabetes and learned that insulin sensitivity varies with menstrual rhythms?
And what if you were plagued by other miseries, like migraine headaches or yeast infections or systemic lupus erythematosus, that also seem to wax and wane along with the menstrual cycle?
Would you use menstrual cues to time your surgery, to watch your blood sugar extra closely, or to predict the onset of troubling symptoms?
Chances are you would — in these and many other cases.
In fact, if you’re among the millions of women who have not yet hit menopause, you’ve probably already become a kind of amateur scientist, searching for connections between your own monthly rhythms and the ups and downs of your health.
The problem is, the medical establishment hasn’t exactly shared in this enthusiasm for finding links between menstrual rhythms and patterns of disease. Until recently.
Like the circadian, or daily, rhythms now known to be part of many basic biological processes, like hormone secretion and temperature control, our bodies also have longer rhythms, none more obvious than the menstrual, or monthly, cycle.
To be sure, the question of why humans and many other primates menstruate — pass blood from the uterus periodically when conception does not occur — is still an open one.
Perhaps evolution just isn’t done with us yet. In fact, if women held the evolutionary cards, maybe we’d get rid of menstruation, especially if we could have babies without it.
Or perhaps menstruation, just as the textbooks say, is what happens when something else — conception — doesn’t happen, though in energy costs to the body, it seems a high price to pay for a fancy reproductive design.
Or perhaps, as maverick scientist and MacArthur “genius” award recipient Margie Profet contends, menstruation is the female’s way of getting rid of all sorts of nasty bacteria and other pathogens that ride into the body on the tails of sperm.
Profet, an enthusiastic visiting scholar at the University of Washington in Seattle and author of a controversial article on menstruation three years ago in the Quarterly Review of Biology, thinks menstruation, far from being an evolutionary accident, is a nifty adaptation to the threat of infection.
Citing evidence from numerous species, including those that may menstruate invisibly, she says that “sperm are vectors of disease” and that menstruation exists “to protect the uterus and oviducts from colonization by pathogens.”
Whatever its reason for being, the menstrual cycle in humans is a lot more complex — and potentially more closely linked to the rhythms of health and disease — than scientists used to think.
Susceptibility to AIDS infection, for instance, may vary as hormone levels fluctuate across the menstrual cycle.
In May, scientists at the Aaron Diamond AIDS Research Center in New York and the National Institute of Child Health and Human Development found that monkeys given a high dose of progesterone were more likely than other monkeys to become infected by SIV, the monkey AIDS virus, following vaginal exposure to the virus.
Cindy Pearson, executive director of the National Women’s Health Network, notes in a soon-to-be-released newsletter that this study involved monkeys, not women; SIV, not HIV; and progesterone implanted in pellets under the monkeys’ skin, not the body’s own natural surges of the hormone.
Still, the network is “extremely concerned” because the study showed that when progesterone is high, vaginal tissue thins, perhaps making it easier for the AIDS virus to gain entry.
This suggests that women who have sex with HIV-positive men might be more vulnerable during the second half of their cycles, and that women using progesterone-based birth control, such as Norplant and Depo-Provera, might also be at extra risk.
And there are other potential links between health and menstrual rhythms, though the quality of the research varies from study to study, says epidemiologist Sioban Harlow of the University of Michigan, who has combed the medical literature looking for such links.
Basic metabolic rate, for instance, appears to be higher in the second half of the cycle, with women often consuming — and expending — 500 extra calories a day. “You’re hungrier and with reason, not because of lack of will power,” says Harlow.
Immune function also seems to fluctuate with the time of the month — in still-perplexing ways. Some researchers say progesterone acts as an immune suppressant; others have found that infection-fighting white cell counts are lowest when estrogen is highest.
In one study, Dr. Barbara Mittleman, an immunologist at the National Institute of Mental Health, found that the kind and degree of immune fluctuation across the menstrual cycle seems to vary from woman to woman.
Yet some auto-immune conditions clearly wax and wane with menstrual rhythms, among them rheumatoid arthritis and systemic lupus erythematosus, says Dr. Balu Athreya, a rheumatologist at Thomas Jefferson University in Philadelphia. The worst flare-ups of lupus, for instance, often come in the luteal phase.
And with arthritis, some hormones — like those in pregnancy — often offer relief, while those of lactation may make it worse.
Asthma, too, seems to flare just before menstrual periods, many women say, though a 1989 review found that detailed studies on the subject showed no clear pattern.
It has also been shown that progesterone, the dominant hormone of the second half of the cycle, can trigger adverse changes in cholesterol, says Dr. JoAnn Manson, co-director of women’s health at Brigham and Women’s Hospital. Because younger women are at low risk of heart disease to begin with, however, these fluctuations may not pose a huge risk.
Far more likely to cause grief are migraine, acne, panic attacks, changes in bowel function and an increased tendency toward epileptic seizures — all of which have been shown to get worse before a woman’s period, says Dr. Karen Carlson, director of Women’s Health Associates at Massachusetts General Hospital and a co-author of the Harvard Guide to Women’s Health.
Diabetic women, too, may have an extra tough time just before their periods, she says, because progesterone increases resistance to insulin. This means it takes more insulin to get sugar into cells — so diabetic women may need to increase insulin as their periods approach.
But of all the potential links between menstrual rhythms and health, perhaps none has greater implications than the timing of breast cancer surgery to ovulation.
“This is really where the rubber meets the road,” says Dr. William Hrushesky, senior attending oncologist at the Samuel Stratton Veteran’s Administration Medical Center in Albany, N.Y.
For years, says Hrushesky, the idea that the timing of breast surgery might be important was greeted “with ridicule; then [it] went to outright hostility, then has been ignored.”
But even skeptics like Dr. Kent Osborne, chief of medical oncology at the University of Texas Health Science Center in San Antonio, now say “what’s really needed is a prospective trial” in which menstrual data are correlated with timing of surgery and results are compared.
So far, there have been about 20 retrospective studies in women with breast cancer. About a dozen of them have concluded that, at least in women whose cancer has spread to underarm lymph nodes, the best time for surgery may be just after ovulation, when estrogen is falling and progesterone is surging. This is the early part of the luteal phase, or second half, of the menstrual cycle.
In 1991, an American study of nearly 300 women found the luteal phase was best for surgery, as did a British study of nearly 250 women. In a 1994 study, the British team noted that the high progesterone in the luteal phase seems to contribute to “significantly better survival.”
A 1994 Italian study of nearly 1,200 women came to a similar conclusion, finding that women who had surgery in the luteal phase had a “significantly better prognosis” than those who had surgery in the follicular, or first half of the month.
Some other studies have found no relationship between the timing of surgery and prognosis, but there are theoretical reasons why there might be a connection.
In the first half of the cycle, women have high levels of estrogen without any accompanying progesterone. Estrogen can trigger a tumor growth factor called IGF-1 and may increase enzymes like cathepsin-D that help cancer spread.
By contrast, there are hints that progesterone may damp down such enzymes and keep small blood vessels from leaking cancer cells into the bloodstream. Both estrogen and progesterone may also influence immune response to cancer, though how this plays out across the menstrual cycle is difficult to pin down.
The bottom line, as the Society for Menstrual Cycle Research has been saying for nearly 20 years, is that more research is needed into the menstrual cycle’s effects on health.
Until that research is done, one of the best things you can do for your own health is to keep records of recurring symptoms and chart them against your menstrual cycle.
Whichever way your data turns out, says Carlson, you’ll get valuable information. You may find some connections with menstrual rhythms that you never suspected.
And some troubles that you might have linked to monthly periods may turn out to be utterly random strokes of fate.
SIDEBAR:
The premenstrual syndrome paradox
One of the most controversial conditions linked to menstrual rhythms is PMS, or premenstrual syndrome, now also called premenstrual dysphoric disorder.
Politically, PMS represents a no-win situation for feminists.
The risk in legitimizing it is in “medicalizing” the normal menstrual process and potentially branding all women as sufferers of emotional distress before their periods, says Ann Voda, director of the Tremin Trust Research Program on Women’s Health at the University of Utah College of Nursing.
On the other hand, failing to recognize the genuine suffering of some women — perhaps 5 to 8 percent, according to Nancy Fugate Woods, director of the center for women’s health research at the University of Washington in Seattle — is no solution either.
Clearly, some women do have a terrible time as their periods approach, with bloating, breast tenderness, irritability, changeable moods, depression and fatigue among the symptoms.
One hypothesis is that this misery is caused by low levels of the brain chemical serotonin, though this is not proved.
Still, for some women, the premenstrual time does seem to be “almost a serotonin-deficiency state,” says Dr. JoAnn Manson, co-director of women’s health at Brigham and Women’s Hospital. And some, she says, get “a good response to Prozac,” an antidepressant drug that increases serotonin levels.
For others, the anti-anxiety Xanax taken for a week before the period may also help, says Dr. Karen Carlson, director of Women’s Health Associates at Massachusetts General Hospital.