The English edition of Is Menstruation Obsolete? skillfully co-opts the women-centred literature on menstruation. For example, it mentions Emily Martin's anthropological work about the language used to describe women's bodies 24, and Sophie Law's Issues of Blood 25. The forward, by a woman with a masters in public health, discusses the importance of menstruation to women's cultural and emotional identity. Although it is thus oddly spiced with social science, this book has a strong biomedical perspective that menstruation is "needless"(p. 159) and "harmful"(p. 5) 3. This is not new. Similar cultural notions are part of our daily lives as women - menopause needs "replacement" hormone therapy, successful pregnancy and delivery need hormonal or surgical intervention and PMS is a disease well treated by Prozac & Mac 226;26. Much of women's lives, especially the reproductive aspects, are viewed as a disease or deficiency state. Should it surprise us that menstruation, too, is perceived this way?

Women who have the most difficulty with their cycles are adolescent and perimenopausal women. In both, high estrogen levels and ovulation disturbances are common 13,27. Most menstrual cycle related problems (heavy flow, premenstrual symptoms, cyclic migraines, breast nodularity and pain and even severe cramps), like endometrial hyperplasia and cancer, are related to abnormal cycles. Their root cause is too little progesterone for the level of estrogen 22. Paradoxically, this book proposes to get rid of menstrual flow by giving the high dose estrogen and progestin therapy in oral contraceptives. You should be aware that, although newer contraceptives are called "low dose," even the 20-35 microgram estrogen pills provide estrogen levels approximately four times natural, menstrual cycle levels.

I think it is perfectly acceptable and feasible to continue a conventional oral contraceptive pill for an additional week or two. Camping in bear country is a good reason given that menstrual blood may cause aggression in these wild animals. This should be an exception, not the rule. I have significant doubts about the feasibility and safety of continuous birth control pills. Progesterone and progestins, given continuously, cause a thinning of the endometrium (uterine lining) so there is little or nothing to shed as a period. However, continuous birth control pills provide high estrogen and progestin levels that usually thicken the endometrium. There is a high risk of irregular bleeding and the three-monthly flow is likely to be heavy and miserable. Unpredictable flow is a hundred times worse than cyclic ovulatory menstruation. Breast soreness is also likely and nausea, weight gain and fluid retention in some women would likely be magnified by daily therapy. In the real world, sore or nodular breasts (which raise the specter of breast cancer) and spotting or irregular flow (causing worries about endometrial cancer) will lead to skipped pills 28 and lost contraceptive effectiveness.

I'm also peeved at the about-face of medical experts who, in the '80s, blamed women for exercising and skipping periods. They are now telling us to use excessive exercise (under a doctor's orders) or daily birth control pills to produce amenorrhea 3!

Ironically, we don't even know the normal variability of menstrual cycles of populations of women of different ages. We need long term information about women's cycles just after menarche, in their 20s, 30s, 40s and entering perimenopause. However, doing the longitudinal population based studies that would provide this information is not a priority for research granting bodies. I would like to know how many such proposals have been rejected by the Medical Research Council of Canada (MRC) and the U.S. National Institutes of Health. (I know of several on which I wasted months of work). To achieve health for women we need this information because silent ovulatory disturbances (in regular cycles with normal estrogen levels) are associated with significant bone loss [8]. To date, that study we began 15 years ago is the only one to systematically and continuously document menstruation and ovulation over a year in a large number (66) of women. Given that the new Canadian Health Research Institutes (a replacement for MRC) is apparently not to have a Women's Health Institute, these crucial but expensive studies may never be done. Furthermore, 86% of Canadian premenopausal women have used the birth control pill for three or more months (Prior, unpublished data from the Canadian Multicentre Osteoporosis Study, 1998). Therefore, we may never know what is truly normal (in other words, for women not exposed at a young age to high and suppressive estrogen/progestin levels).

Instead of suppressing periods, we should learn more about, and treat, ovulation disturbances. Our studies show that ovulation disturbances are common and occur in over 35% of regular cycles in healthy women [29]. Worry, such as concern about gaining weight, or feeling you need to restrict food (although your weight is normal) is related to ovulation disturbances [29-31]. Worry about eating is also associated with higher cortisol production and potential bone risk [32]. In addition, disturbed ovulation with adequate or high estrogen levels is related to a significant increased risk for breast cancer [33-35]. Finally, we now know that PMS is caused by estrogen excess or inadequate progesterone levels [36]. Recognizing, first, and then treating ovulatory disturbances (with cyclic progesterone or medroxyprogesterone "replacement") until the root cause is corrected [22,23] would fix problems blamed by Coutinho and Segal on periods.

In summary, I believe that the amazing interplay of many hormones creating the ovulatory menstrual cycle is important for far more than making babies. Ovulatory menstrual cycles teach us as women to be adaptable and to tune into what is really important. We learn to adjust our lives and responses to our changing internal environment. This greater flexibility serves our culture well by helping us cope, for example, with the fulfilling chaos of raising children. It also allows us to be adaptable and therefore more able to resolve conflicts. In addition, normal menstrual cycles potentially allow us to feel in touch with environmental rhythms and also serve as a reminder that freedom from worry as well as lack of illness are necessary for health. When we don't understand the whole, it is wise to collaborate with rather than seek conquest of nature. Therefore, my response to women offered the "opportunity" of no periods is to be cautious. I personally, recommend women "Go with the flow!"

Jerilynn Prior is a Professor of Endocrinology at the University of British Columbia and an internationally known expert on ;women's health.

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