Tetanus shots prevent tetanus, but no one goes out and stabs themselves with a rusty knife after getting one just to see if it took.
Anyone who is old enough to get birth control pills knows the consequences of sexual intercourse. There is an absolute and unique relationship between sex and pregnancy. Sex leads to pregnancy, pregnancy implies sexual intercourse (actual or constructive). No other options. Further, sexual intercourse is an intervening freely made decision between the "medication" and the increased risk of illness. A person who should be using asperin therapy might suffer a heart attack just by sitting up too quickly in bed. A woman is not going to become pregnant (and suffer the increased health risks) by bending over to tie her shoes.
Equating pregnancy with an illness like impotency is absurd. One is a consequence of free choice, the other is a consequence of a number of unknown factors.
Well all I can say is - if a womanís pregnancy caused menís balls to shrivel up and become useless raisins - depriving them of any kind of a sexual life , then funding to distribute free birth control would shoot out the asses of Congressmen. Oh wait - on second thought, pregnancy already does that. Never mind.
If you're not part of the solution (birth control), then you're part of the problem (Viagra). ;)