I don't know what the "sex balance" is. But physiologically, everyone that wants to have sex wants to reproduce. If their mind does not want to reproduce they are psychologically messed up and their mind and body are in conflict. I predict that a male form of chemical birth control will either pander to the anti-natal psychological disorder (infantile lust) or destroy the sex drive (ex. Depo Provera is used for chemical castration) either way, it will exacerbate the conflict between mind and body and further destroy relationships between the sexes.
People do not want every sex act to result in pregnancy, for most people, 2 or 3 of those in a lifetime is enough.