› firstname.lastname@example.org 
In last week's response to "Pill or No Pill," I'm glad that you mentioned that playing around with endocrine systems can be harmful. When I was diagnosed with anorexia, the doctors told me that if I kept missing periods, I would be at risk for things like low bone density and osteoporosis. It seems suspect that doctors and pharmaceutical companies are now advocating pills that limit a woman's period to four times a year. What can you tell me about it?
Keeping My Period
PS In regard to "Pill or No Pill," why can't they have sex during her period?
I don't get a chance to say this very often, but your doctors misspoke. There's no doubt that your endocrine system was messed up good while you were anorexic, but it wasn't the missing periods that were doing the damage. Both the amenorrhea (lack of periods) and the potential bone loss were symptoms of messing with your endocrine system. When one hormone gets knocked out, the entire chain is broken, and all sorts of havoc potentially ensues. You weren't menstruating because you weren't ovuutf8g because your ovaries weren't getting the right hormonal cues because your pituitary gland wasn't sending them because your hypothalamus wasn't sending them because you were starving. It's actually a good idea, if you're an ovum, to avoid getting ovulated and fertilized while there's no good material with which to build a baby.
Somewhere in there your ovaries also failed to get the hint to produce lots of estrogen, which is required for the absorption of calcium, and there go your bones. So yes, of course it's potentially dangerous to mess around with your endocrine system, but we should remember that millions of women do just that every day when they take their pill, and they're just fine. Better, even, since they're not having to squeeze out another baby every year or so for the entire span of their reproductive years, the way our "ansisters" did and as women still do wherever reliable birth control is unavailable or forbidden. And speaking of our ancestors ...
We (the Western, industrialized, supermarket-shopping we) are the freaks in a long line of normal people. As any number of evolutionary biologists and other researchers have pointed out recently, it is not at all the natural state of women to menstruate every damn month for 45 (damn) years. Contemporary hunter-gatherer (mostly gatherer) women start late, have a bunch of babies, breast-feed them forever, and die young, totaling about 100 or 150 periods in a lifetime. By contrast, supermarket women reach for the tampon box approximately 450 times. No wonder we're crabby.
So is menstruation natural? Well, obviously, but an argument can be made that not menstruating is even more so. What seems a brute biological fact ("women bleed every month") turns out to be in part a social construct. Isn't that cool? This sort of thinking isn't really new the developers of the original pill built in the bleedy part, the placebos at the end of the cycle, because they thought not menstruating would freak women out, not because it was medically necessary but it's not the sort of thing people tend to talk about. It will be, though, by necessity, and soon. As new products make four periods a year or no periods a year (seriously, this one has been extensively studied and so far so good for safety) increasingly popular, menstruation will become a lifestyle choice like any other. This will disgust the more moon-goddessy type feminists and please the "it's all about choice" ones. For everyone else, after a while, it will just seem, well, natural.
You also asked, very reasonably, why the couple in the original letter (she wanted to take something to suppress her periods so they could have romantic weekends) couldn't just have sex, blood or no blood. The answer is they could, of course. I'm willing to bet that they hadn't even discussed and dismissed that option, as "no sex when the painters are in" is just one of those things everybody takes on faith until they don't. If a woman's "monthlies" turn out to be at least partly a social invention, the menstrual taboo is entirely one. Barring the presence of something nasty, blood-borne, and contagious, there's no reason on earth (or the moon, for that matter, and aren't we going back soon?) why a couple can't have a threesome with him, her, and Aunt Flo.
Speaking of the moon: women down here have connected their sexuality and fertility with the phases and pull of our satellite for so long that I have to wonder what happens to all that lunar blood magic when we're living in bubbles on the moon. Nothing takes the mystery out of a hunk of rock and dust like having to dig holes in it to build a privy.
Andrea Nemerson has spent the last 14 years as a sex educator and an instructor of sex educators. In her previous life she was a prop designer. And she just gave birth to twins, so she's one bad mother of a sex adviser. Visit www.altsexcolumn.com  to view her previous columns.