This article explains the reasons for shifting hormone changes in women, aside from pregnancy.
A woman’s hormones would do just fine if all they had to do were worry about themselves. They would just go on their jolly cyclic way, rising and falling, taking the menstrual cycle on the reproduction-readiness merry-go-round until pregnancy would occur. Unfortunately, it’s a polluted environment in which hormones try to do their job. The perfect system is besieged from all sides by weight, exercise, behavior, drugs, and less than optimal circadian rhythms in today’s after-work “second day” of nighttime entertainment.
It used to be that when dawn arrived, the men would go off to the hunt while the women tended to the children. When the men arrived that evening with the food, the women prepared it, all ate, and then all fell asleep, exhausted. It was work all day and sleep all night. Even with the advent of farming, the work and daily activities were by the light of the sun, and at night everyone slept.
Today there are over a hundred cable channels, bars open till two, late movies, late dinners, dancing, hanging out-all of the modern entertainment obligations if we want to lead a “full” life. Unfortunately, we one-life humans try to lead a two-life existence on one circadian rhythm. Our hormones, meanwhile, still adjusted to hunting wild boars by day and sleeping by night, carry on as best as they can. The hormones of yesteryear think the lifestyle of today is crazy.
But being human does have its advantages. We do in fact have a great big brain that allows something the other animals don’t have – flexibility. When life becomes more complicated, we adjust because we can. The bedlam of hormonal mismatches isn’t all that mismatched after all. We do get along fairly well, even trying to cram two lives into one.
Except for the extremes.
We are certainly creatures of this world, and it is no coincidence that the menstrual cycle follows the lunar months. Even our pineal glands, which make melatonin for pigment, are related to the cycling of life on this night and day Earth. Our hormones, although they think we’re crazy, still do a good job in being flexible themselves with our new modern post-Iron Age lifestyles. But even biological rhythms have their limits. Extremes of weight (high and low) and extremes of activity will alter even the most reliable of female hormonal cycles.
In the normal unchallenged menstrual cycle, low amounts of estrogen and progesterone trigger hormones from the hypothalamus and pituitary to stimulate the ovaries to make more. When the estrogen rises, this stimulates a follicle to nurture a developing egg for ovulation. When ovulation occurs, the follicle remains to make progesterone, which maintains the richness of the uterine lining in preparation for a fertilized egg. When this doesn’t happen, the hormones fall, the lining falls apart and away (the “period”), and the hypothalamus and pituitary are again stimulated to make hormones that will incite the next cycle. And so on.
Obesity can affect the cycle by accidentally converting adrenal hormones into estrogen. This steady stream of constant estrogen will muck up the works of the rising and falling ovarian cycle. This can result in irregular bleeding over long periods of time, or worse, over stimulation of the uterine lining which can become pre-cancerous.
Extremes of exercise – running many miles a day or participating in the numerous extreme competitions – will decrease the hormonal levels, particularly progesterone by a complex scenario in which a woman won’t ovulate regularly. The end result is much like that for obesity, in that there is either irregular bleeding or no bleeding at all.
There seems to be a critical weight below which the hormones won’t function normally. In medical school we were taught it was 106. But practicing obstetrics for twenty years has seen many under-100 not only cycle normally but become pregnant without difficulty. But there is something to a critical weight – it’s just not 106 in everyone. A woman who is underweight and also exercises to an extreme will carry a double-whammy in menstrual irregularities.
Drugs can alter the cycle as well. Thyroid medicines, steroids, and the so-called “natural supplements” can alter hormonal function. The recent rage in “nutritional aids,” like the Ma Huang-containing products, may even add extra danger as undiluted ephedrine (an adrenaline-like substance) can alter heart function as well. Most of these products are sold by non-medical people, escaping the scrutiny of the FDA because of their “nutritional” labeling. This loophole has extended into hormonal therapy, with “natural” hormones doing everything from absolutely nothing to increasing breast size temporarily.
Now I’m the first one to say I’ll take my air conditioned home with city services over cave-living, but the further we get away from our true circadian and natural lives, the more our internal systems have to adjust to the new world orders. Women are pretty important – and not just for reproduction! But the reproduction is a deal-breaker if we want to survive. We can reset the thermostat with some flexibility, but there are limits beyond which the system won’t work.