[citation][nom]Rab1d-BDGR[/nom]It may not sound appealing, but consider that most other attempts at finding a male contraceptive involved drugs that mess around with hormones. Messing around with hormones can have untold effects - just look at the original femal contraceptive pills, until they got the ballance of estrogen and progesterone correct there were all sorts of problems, not least endometrial cancers. Even modern hormonal contraceptives are frought with problems.As for calling this eugenics - Are female contraceptives, condoms or abstinence programs also "eugenics"? Nope, not unless it is forced on people against their choice.[/citation]
Female fertility is governed by a very specific interaction between four hormones that much occur at a specific time for the woman to ovulate and have the lining of the uterus be receptive to implantation of a fertilized egg. Interrupting this hormonal cycle is the most logical way to try to obtain female contraception without using physical barrier methods. The problems with the initial oral contraceptives mostly had to do with the fact that the optimal dose hadn't yet been determined. Modern combination estrogen/progesterone OCPs have 20-35 micrograms of estrogen, while the initial ones had 100 mcg. That mostly just caused the women to get nauseated, and doses were shortly changed to 50 mcg and then to 35 mcg. There are still some problems with modern female hormonal contraception (such as the risk of blood clots if you're a woman over 35 and smoke while taking a standard combination estrogen/progestin product), but they are relatively minor.
Male contraception on the other hand is much more difficult. We do not have a complex hormonal cycle that makes us fertile at certain times and not others that we can interrupt. Any effective attempt to stop sperm production via hormonal methods are very anti-androgenic and lead to very notable side effects. You lose your sex drive, lose muscle mass, and have breast enlargement. So, a working method of non-barrier contraception in men would need to be non-hormonal in action. The only one I have heard of that is even moderately effective is testicular bathing, which involves putting the scrotum in ~110 F water for about half an hour per day to kill the developing sperm (sperm hate warm temps, which is why the testicles have to be outside of the body cavity.) I wish Gates' guys luck, but I'm not getting my hopes up too much as the physiology of male contraception makes it a real tough nut to crack.