Angela, Here's the explanation as to how the methods that I listed are supposed to influence what happens to the sperm.
According to the theory, male (Y) sperm are faster but more fragile than female (X) sperm. Further, acidic environments harm Y sperm, according to the theory, making conception of a girl more likely. The Shettles method aims to exploit these two factors.
The Shettles method differs from the Ericsson method, in which the semen is deposited outside the woman and time is given for the fast/slow swimmers to separate before artificial insemination takes place.
[edit]Timing of Intercourse
In order to have a boy insemination should occur as close as possible to the moment of ovulation so that the faster, Y-sperm arrive first and achieve conception, according to the theory. When seeking a girl insemination the couple should seek to have sex 2½ to 3 days before ovulation.
[edit]Sexual Position
Shallow penetration coupled with the sperm deposited close to the entrance favors female conception because the area is more acidic, which inhibits the weaker Y sperm, according to the theory. To allow the Y sperm to reach the egg first (which supposedly moves at a faster rate), deeper penetration should be sought, to deposit the sperm at the least acidic area near the uterus opening.
[edit]Orgasms
Female Orgasm favors male sperm because they make the vaginal environment more alkaline.