This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
Menstruation, as we all learned in junior high health class, is a cyclical process during which the uterine lining is released by the body through the vagina (1). Each monthly cycle is divided into three artificial phases (scientists like to divide and categorize things): menstruation, follicular phase, and luteal phase. During the middle phase (follicular) a hormone that stimulates follicles (eggs) named FSH (Follicle Stimulating Hormone) is released. This causes several eggs in the ovary to mature. Typically only one egg will mature fully and leave the ovary for fertilization. However, several eggs begin to mature to determine which of these eggs is the strongest (much in the same way several sperm are released to fertilize an egg, but only one will succeed.) During this time, the estrogen is being released in higher and higher levels until at the highest level, FSH is turned off and LH (Luteinizing Hormone) is turned on. LH is what causes the egg that is fully mature to leave the ovary and begin traveling through the fallopian tubes to be possibly fertilized. Progesterone is the hormone that is the master hormone of the final phase, luteal phase. Progesterone continues development of the lining of the uterus. If conception does not occur, all hormone levels drop drastically, and menstruation begins (1).
Okay, okay, but you knew all of that already. Or, maybe you knew bits and pieces of it, but not the scientific names for everything. Now the interesting part begins. We know that all women go through this cyclical process, be they fertile or infertile. Further, we also know that this process is necessary for fertility. The question now becomes not one of menstruation as a necessity for life or reproduction, but a question of how many cycles a woman has during her life span.
In 1986 a scientist named Beverly Strassmann, who is an anthropologist at the University of Michigan in Ann Arbor went to Africa to study menstruation. She specifically chose the Dogon tribe of West Africa. The village, Sangui, is located about a hundred and twenty miles south of Timbuktu (now that's out of the way!). The Dogon grow millet, sorghum, and onions, raise livestock, and live in adobe houses. They use no contraception (2). These people live as their ancestors have lived for centuries.
The fact that this tribe has not modernized made it extremely interesting to Strassmann because she wanted to build a composite of what the lives of pre-industrial fertile women might have been like. The Dogon had one more aspect that made them particularly interesting to Strassmann: they utilized menstrual huts (2). Women slept in these huts during their menstrual periods making it extremely easy for Strassmann to chart the cycles of all the women in the village. Strassmann took urine samples from the women to insure that they were menstruating. She then made a list of all the women in the village and kept track of everyone who visited the huts. She did this for the two and a half years she lived with the Dogon.
Among the Dogon she found that a woman, on average, has her first period at the age of sixteen and gives birth eight or nine times. From age 16, at the onset of menarche, to age twenty, the Dogon woman would average seven periods a year. Over the next decade and a half, from the age of twenty to thirty four, she sends so much time either pregnant or breast feeding (which, among the Dogon, suppresses ovulation for an average of twenty months) that she averages only slightly more than one period per year. Then, from the age of thirty-five to menopause, during which time her fertility rapidly declines, she would average four periods per year (2). In total, Dogon women had approximately one hundred periods in their lifetime (with the women living to be approximately seventy or eighty years old). In contrast, modern, Western women average about five hundred times during her lifetime (1). I am going to suggest that the difference between one hundred and five hundred menstrual cycles is a drastic difference with implications for women's health.
Strassmann believes that the number of lifetime menses is not affected by differences in diet or climate, but instead by things such as age of menarche, number of children borne, prevalence of wet-nursing and sterility are more significant factors. Further, she believes that the pattern of late menarche, many pregnancies, and long menstrual-free stretches due to breast feeding was virtually universal up until the transition from high to low fertility (2). Basically, the number of periods we think of as normal (500) is in evolutionary terms abnormal.
Two doctors, Drs. Elsimar Coutinho and Dr. Sheldon S. Segal have argued that what they call "incessant ovulation" is a serious problem for women's health. Menstruation involves discomfort for a majority of women (1), it involves extreme mood shifts, migraines, endometriosis, fibroids, and anemia, one of the most serious health problems in the world. The loss of nutrients in the menstrual blood (most significantly, iron) are noticeable for menstruating women. Most serious of all, however, is the risk of cancer. Cancer occurs because as cells divide they sometimes make mistakes that cause new cells to divide uncontrollably (3). One of the reasons the risk of cancer increases as age increases is that the cells have more time to make mistakes (2). This means that promotion of cell division on a incessant basis has the potential to increase cancer risk. Ovulation appears to be one of those instances.
Whenever a woman ovulates, the egg literally 'erupts' through the wall of the ovary (4). To heal that puncture, the cells of the ovary wall have to divide (2). Every time a woman gets pregnant, her risk of ovarian (and uterine and endometrial) cancer decreases by about 10% (2). Why? It could be that with the suppression of ovulation and menstruation associated with pregnancy and breast feeding saves the ovarian and uterine walls from many bouts of cells division. Breast cancer rates also drop dramatically with pregnancy also, but for a different reason. Bearing children turns out to be protective because in the last two trimesters of pregnancy the cells of the breast mature and become much more resistant to mutations (2).
Enter the birth control pill. Since we live in a modern day and age when women cannot be expected to be ordered by their doctors to remain home 'barefoot and pregnant' (although I know the Righteous Right would just love to do just that). Birth control pills are composed of low dosages of estrogen and progestin. Progesterone, as mentioned above, maintains the lining of the uterus in order to prepare the uterus for implantation of a fertilized egg. It assumes the pregnancy of the woman, and so stops the ovaries from releasing new eggs (2). When a woman is on the Pill, of course, these hormones are not surging. They are being given in steady doses so that ovulation is permanently shut down. The estrogen included in the pill helps to hold the endometrium together, and it also maintains other tissues as well (most interestingly, brain cell synapses) (2).
Now, birth control pills today include a seven-day period during which no hormones are taken so levels will drop and the endometrium flushes out of the body in a period. However, as noted by women who take the Pill, these periods are lighter and easier than normal periods. Because the fluxes of estrogen and progesterone that cause the lining of the uterus to grow are dramatically reduced, since the Pill slows down the ovaries (2). These lighter periods are healthful because not so much iron and other nutrients are lost. However, the monthly period is not medically necessary. The effect of the Pill on the endometrium is so modest, women could go for months without having to menstruate. However, the inventor of the Pill feared that women would find this unnatural and disturbing (2). A monthly period is also a reassurance that she is not pregnant. These sentiments may have been understandable, particularly in the time era during which the pill was invented, however, today in our modern era it is conceivable that women no longer have to endure the monthly 'curse' they so frequently complain about.
There are many, many reasons the Pill is beneficial. Birth control and regulation alone would make the Pill valuable. However, today in our modern age, with high rates of cancer and anemia, and low rates of fertility, women are the losers in the game of health. As women are discovering the products they use for their menstrual cycles frequently contain hazardous materials, as rates of cancer increase, and as women decrease their fertility rates ever lower the danger to their health becomes greater. Further, it appears that all of this may be unnecessary.