Why does women birth control not cause gonadal atrophy and suppression like man’s TRT does?

Question

If I understand correctly, birth control is estrogen in a pill. It should be an exogenous hormone to the female body, just like testosterone from TRT.

Long term TRT causes testicular atrophy, and going off is quite hard, because the body basically shut down endogenous production of testosterone.

So why do women seem to be able to come off birth control easily without having low estrogen problems?

In: 2

Answer 1

Birth control isn’t just estrogen in a pill. It’s estrogen and progesterone in a pill. The female body uses varying levels of estrogen and progesterone to signal things during menstruation and pregnancy. There’s no one set level where estrogen and progesterone should always be. During pregnancy for example progesterone skyrockets. What this means is that birth control causes the body to be quite confused about which phase its supposed to be in, but it doesn’t push estrogen levels beyond what could be naturally occurring.

There are also phases when naturally occurring estrogen and progesterone are quite low as part of normal signaling. In particular, right before menstruation, estrogen and progesterone both dramatically drop as a signal to begin a period. This leads to a number of interesting tricks that many women can do with using oral birth control pills to manipulate their menstrual cycle. For example some women can use specific dosing schedules of estrogen and progesterone to eliminate that drop and never have a menstrual cycle. Other women use abruptly stopping taking birth control as a way to rapidly reduce estrogen and progesterone and thus induce a menstrual cycle in a few days.

This whole system works because estrogen and progesterone levels are supposed to change rapidly in female bodies and the body is meant to adjust to these constant changes. Nothing shuts down permanently because the metaphorical equipment is made to be adjusted constantly. Testes are not designed to do these kinds of rapid shifts. The male body does not regularly go into states of very high or very low testosterone production as part of normal life.

It should also be noted that progesterone is actually more important to this than estrogen. There are some forms of birth control that are progesterone only. There are not estrogen only birth control pills. Taking estrogen alone doesn’t have the same degree of effect on manipulating menstrual cycles.