There are two types of sperm, one carrying the X chromosome, and one carrying the Y chromosome. The type of sperm that fertilises the egg, and determines what sex the baby will be (X for a girl, and Y for a boy). Dr Shettles, author of the best selling book, How to Choose the Sex of Your Baby, believed that the types of sperm had a number of inherent differences. Through research, he found boy sperm to be weaker, smaller and faster than their female counterparts. He discovered that female sperm were more resilient and able to survive for longer periods inside the female body.
Positions Please Dr Shettles believed deep penetration was important to give the boy sperm a head start. With less difference to travel, the boy sperm would be able to outswim the girl sperm, and find the egg. The Shettles method claims that to improve your chances of conceiving a boy, you should have sex in positions that allow for deep penetration. It may not sound very romantic, but the closer to the cervix the sperm are ejaculated, the more likely they are to find the egg. Here are some position which can help accomplish this
Doggy Style The position most commonly mentioned during discussions of this nature, is doggy style. This position allows for deep penetration, and is touted by many as the optimum position in which to conceive a boy. You should kneel on all fours, and have your partner enter you from behind. You could also adjust this position so that you are kneeling or leaning over a raised surface, if you prefer