Take Your Position
Another popular school of thought says that certain sexual positions can improve your odds of having a boy. In ancient times, beliefs abounded about the positions that would lead to male offspring, such as having intercourse with your heads pointing north or having the would-be mother sleep on the left. Discoveries in science over the centuries have led to somewhat more complex theories about positioning (and a lot else). For one thing, we now know for sure it’s the male who determines the sex of a child. The mother always provides an X chromosome in the egg; the father contributes either an X chromosome (yielding XX = girl) or a Y chromosome (yielding XY = boy). Each individual spermatozoa carries either X or Y and the baby’s sex depends on which one penetrates the egg most effectively first.
According to Dr. Landrum Shettles, MD, author of How to Choose the Sex of Your Baby, deeper penetration during intercourse seems to favor boys.
He explains that a woman’s vagina is most acidic near the entrance, and—as mentioned before—some evidence suggests male sperm don’t fare well in acidic environments. Shettles says deeper penetration puts sperm closer to the egg, reducing the distance the sperm have to travel through the acidic vagina. This gives faster-swimming Y-chromosome (male) sperm a head start over the X-chromosome (female) sperm. Therefore, he recommends rear-entry intercourse for couples who want a boy. (Do I really have to clarify “rear-entry”? OK, fine … he’s talking about “doggy-style,” people. There, I wrote it.)
Get the Timing Right
Other medical experts also believe that Y sperm (boys) swim faster than X sperm (girls). However, girl sperm typically are more robust and live longer in the reproductive tract than the boy sperm.
So what does this theory mean to you? In a nutshell, if you’re hoping for a boy you should try to abstain from sex for several days before ovulation and then have intercourse as close to ovulation as possible. This increases the likelihood that the boy sperm (the faster swimmers) will beat out the girl sperm to the egg, and not have to survive too long while waiting around for the egg to show up. You’ll have to do some very careful calendar watching or take an ovulation test to determine precisely when you’re ovulating.
Boxers or Briefs?
Sperm are stored “outside” the body for a reason. They can’t tolerate excessive heat and the testicles’ independent structure and considerable surface area keep them safe from the elevated core temperatures inside the body. Some people claim that Y-chromosome sperm (boys) are even less tolerant of heat than X-chromosome sperm. So, if you’re trying for a boy, ask your mate to wear boxers for a while. This will keep things cool and give his “boys” some breathing room.
A cool bath or an ice pack to the scrotum would take matters further, but it’s probably a rare male who would be that keen on producing a son.