Hee.. this is wat i read from the web.
The Shettles Method
Dr. Shettles asserts that XY (boy-making) sperm are faster than XX sperm, but that they die out faster. XX sperm, the kind that makes girls, are slower than XY sperm but hardier - meaning they are more able to withstand the acidic environment of the cervix, so they can hang around longer. If you desire a boy, according to Dr. Shettles, you should:
* Time intercourse as close to the moment of ovulation as you possibly can (you can determine ovulation time by using ovulation predictor kits or charting your basal body temperature). The idea behind this is that since the XY sperm are faster, they're more likely to reach and fertilize the egg first.
* Have intercourse in a position that allows the deepest penetration possible, such as rear entry or "doggy-style." This is because with deep penetration, the sperm will be deposited closest to the cervix where the environment is more "XY-friendly" and the XY sperm will have less distance to travel.
* Abstain from intercourse for four to five days before ovulation, and then only do it on the day of ovulation.
* Make sure the female partner has an orgasm to increase the XY-favorable alkaline secretions in the vagina.
* Avoid heat and tight clothing in the testicular area; these things will kill off the less hardy XY sperm faster.
And to get a girl, according to Shettles, you should:
* Have intercourse two to three days before your estimated ovulation date so that the XY sperm will die out and the XX sperm, since they're hardier, will be able to reach the egg.
* Have intercourse with shallow penetration, which gives the slower but longer-living XX sperm the advantage.
* Avoid orgasm, if you're the female partner, to keep the vaginal environment slightly acidic and friendlier to the XX sperm.
In his earlier publications, Dr. Shettles suggested that to increase the odds of a girl, women should use a vinegar and water douche before intercourse; he has since retracted that suggestion.