So from what I've heard, (preliminary) male birth control is usually based on changing the amount of testosterone a body produces. This hormonal approach is sure to cause side effects, similar to how playing with estrogen levels in women can lead to weight gain, mood swings, etc. I've also heard that staying on male birth control for extended periods of time (several years) can lead to sterility. Anyway, I learned recently that the vagina is acidic, for hygeinic purposes. This acid would kill all sperm, but the testes (or some part of the male sexual anatomy) produces some sort of enzyme that temporarily protects the sperm from acid in the vagina. Sorry for the haziness in this part, but it's from an article that I skimmed last week and now can't locate. Couldn't researchers come up with some sort of drug that blocks this enzyme from being produced? This method seems like it would be much less prone to side-effects, both short and long term. Thoughts?