OK, so you’re trying to get pregnant, but you want to be smart about it. You’ll be happy with a healthy baby of either gender, but you’ve already got two girls so, this time, you’re hoping for a boy. It may sound like an old wives’ tale, but the day you try to conceive could actually play a role in your baby’s gender.

Notice that we said “play a role.” We didn’t say “play a huge role” or “completely and unequivocally determine.” We said it can be a factor.

So, how does this work, exactly? And how could this knowledge have helped the wives of Henry VIII?

Well, there are two types of sperm, you see. There are sperm that make little boys, and sperm that make little girls. Those boy sperm swim faster (on average) than the sperm that product girls. They get to the egg quicker. However, they also burn out faster. They have a shorter lifespan than the sperm that make girl babies. The girl baby making sperm swim slower, but they can live longer.

So, let’s do the math here. If you want to try to influence your baby’s gender, you can pick when to try to conceive. If you’re trying for a girl, have sex a few days before you ovulate. The boy-making sperm will all get to the fallopian tubes, find that there is no egg, and die from despair. If you’re trying for a boy, do it the day before, or even the day you ovulate. That way, the sperm that produce boys will be more viable and more likely to get to the egg first.

Obviously, this depends greatly on you being able to know when it is that you ovulate. If you don’t have a regular 28-day cycle or if you just want to maximize your chances for one gender or the other, get an ovulation test kit to help you figure out when to time your baby dance.

This entry was posted on Tuesday, September 7th, 2010 and is filed under Trying to Conceive.