Want a Boy? Have Sex This Exact Way and You Might Just Get Your Wish

Are you determined to have a baby boy? Depending on who you ask, it's either a complete roll of the dice or a factor you can actually try to control.

For more than 25 years, Dr. Landrum Shettles, author of the bestselling book How to Choose the Sex of Your Baby, has used his trademark "Shettles method" to give couples what he claims is a 75 percent chance of having a child of the desired sex.

Now, his methods have been under scrutiny for years and there's currently no scientific evidence to prove that certain factors — like sex positions — can influence the sex of one's baby, but if you're willing to try anything for a bundle of boy joy, it's worth considering his theory.

There are two types of sperm — one carrying the X chromosome (girl) and one carrying the Y chromosome (boy) — that can fertilize an egg, but Shettles believes "boy sperm" has other differences as well. According to his research, they're weaker, smaller, and faster than "girl sperm," which are more resilient and able to survive longer.

For boy sperm to reach the egg first, Shettles theorized that it was often necessary to achieve deep penetration. These four sex positions that do just that and give those boy sperm a fighting chance:

This position — where your partner enters from behind while you are on all fours — allows for deeper penetration and, as a result, the male sperm get deposited closer to the cervix during ejaculation. The less distance to travel, the better!

Have your partner lift you up, preferably against a wall (no need to risk your safety!), for this position. Although not backed by science, some experts believe the faster boy sperm swim better against gravity.

In this position, you'll essentially straddle your partner — who is either lying down or seated — and lower yourself onto him. This is an ideal option for those who find the aforementioned positions uncomfortable as it offers deep penetration while allowing you to be in control of just how deep.

This isn't a sex position, per se, but some believe that during a female orgasm, an alkaline secretion is released into the vagina, and this shift in pH balance favors boy sperm, giving them an increased chance of survival. For it to work, however, you'd need to climax shortly before your partner does.