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.