Basically, men produce two types of sperms, the X (female) and Y (male). According to Dr. Shettles' studies the y-sperms are smaller, weaker, but faster than their siblings x-sperms, which are bigger, stronger, but slower.
Based on this fact, there are several things you can do to "favor" the conception of boys or girls:
(1) The most important aspect of all is timing of intercourse during the monthly cycle. The closer to ovulation you have sex, the better the chances to have a boy, because the y-sperms are faster and tend to get to the egg first. If you have sex 3 days or more before ovulation, the better your chances to conceive a girl, because the weaker y-sperms tend to die sooner and the x-sperms will be available in greater quantity whenever the egg is released. On the other hand, having sex from 2 days before ovulation, through a few days after ovulation, is better for conceiving a boy. Around the 2-day point -- 48 hours before ovulation -- seems to be the 50/50 mark.
(2) The pH of the women's tract is also very important. A more acidic environment favors girls, since it will kill the weaker y-sperms first, leaving a greater quantity of x-sperms available to fertilize the egg. On the other hand, a more alkaline environment favors boys. Shettles recommends a douche of water and vinegar (acid) immediately before intercourse to favor a girl; a douche of water and baking soda (alkaline) will help for a boy.
(Don't try this without reading Shettles! You have to dilute the douches properly, according to his formula, or they won't help and might hurt you.)
Note: Some women are naturally very acidic and have a hard time conceiving boys.
(3) Position of intercourse and depth of penetration are important, partly because of pH. The closer to the entrance to the vagina, the more acidic the women's tract is. Also, deep penetration places the sperm closer to the egg, and gives those aggressive boy sperms a head start
. So, a shallow penetration will favor girls and a deeper will favor boys. Shettles recommends missionary-position for a girl, and rear-entry (dog-style) for a boy.
(4) Women's orgasms can also be important. It also has to do with pH. When a woman has an orgasm, the body releases some kind of substance that makes the environment more alkaline, favoring boys. He recommends no orgasms when trying for girls!
(5) The sperm count is another factor. Obviously, a low sperm count to begin with doesn't favor either sex. But a high sperm count favors boys. Shettles recommends three things:
a. When trying for a boy, don't have sex for 3- 4 days before you reach the target date a day or two before ovulation! For girls, have sex everyday from day=1 or day=5 ("cleaner"
), and stop 3 days before ovulation.
b. Shettles recommends that for boys, the man wear loose underwear only -- that is, men who usually wear briefs or other tight underwear should switch to boxers. The idea is the same as wearing boxers to increase overall fertility -- the testicles need cooler temperatures for sperms to survive, and the Y-sperms, since they are weaker, will be helped more than the X-sperms by this method. However, Shettles does NOT recommend the opposite, that men wear briefs for a girl -- this will just decrease overall fertility.
c. Also, for a girl, the man is supposed to take a hot bath immediately before intercourse. "Room temperature" is fine for a boy. The idea is the same as the briefs versus boxers -- give the X- sperms an advantage.
(6) Finally, in trying for a boy, Shettles recommends a nice cup of caffeinated coffee for the man, right before sex -- he isn't clear on how or why this works, but apparently it gives the Y-sperms a jolt!
Well, these are the big ones. Read the book for other details. If you can determine the time of ovulation and follow the rules presented in his book, Dr. Shettles claims a success rate of 70-75% for girls and 75-80% for boys (better than the normal 50%). As you see, it's not 100%!!!
Also, Shettles recommends a "practice" period of 3-6 months, to make sure the couple has all the techniques down properly.
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