Natural Sex Selection

I recently purchased the book How to Choose the Sex of Your Baby which outlines the Shettles method to gender selection. The basic premise is that male sperm (XY) are smaller and quicker to reach the egg than female sperm (XX). XX sperm are larger, and therefore, hardier and longer lived than their male counterparts.

The Race is On
According to this theory, if a couple has sex on ovulation day, or very close to it, the chances are very high that one of the quick little male sperm will reach the egg first, and a boy will be conceived. If a couple has sex a few days in advance of ovulation, the male sperm will exhaust themselves and die off after a day or two of hard swimming. This will leave a higher concentration of stronger XX sperm waiting when the egg is released. The chances of conceiving a girl will be much higher in this scenerio.

Acidity Factor
Another big factor in determining which sperm have the advantage is the acidity level of the environment (vagina). Shettles argues that male sperm (being smaller and weaker) have less tolerance for a highly acidic environment than the larger female sperm. They prefer an alkaline space. How is this achieved? Female orgasm. If the woman orgasms during sex before the man does, her vagina will be more welcoming to male sperm. If the woman does not orgasm, the environment will be far more acidic. This will favor the female sperm, making conception of a girl more likely.

Personal Experience
The Shettles method makes a lot of sense to me. We used an ovulation prediction kit when conceiving our son. This pinpoints the hormone surge which precedes ovulation by a day or two. We waited to attempt to conceive that cycle until the hormone surge was detected. This means that the sperm were depositited fairly close to when I was going to ovulate. Viola! We conceived a boy!
I'm not sure if we're going to use the Shettles method or not for our next attempt at conception (whenever that may be). We would love to have multiple boys, but a girl next in line would be comforting. That way, knowing we had one of each, we wouldn't care if the 3rd was a boy or girl. As much as I love my son, I really would rather not have 3 boys. We'll get what we're meant to have, so I don't know if we can really control anything anyway. If the Lord wants me to have all boys, I'll have all boys, and if I'm to have 2 girls and a boy, or 2 boys and a girl, than that's what will happen. The book has been interesting, though, and I've enjoyed reading it.