Do certain sexual positions increase fertility?

Studies of sexual position show that position has no effect on fertility. Almost every time that you have sex, more than enough sperm reach the fallopian tubes where they could fertilize an egg if it is available

Why then don't you get pregnant every month that you time intercourse to coincide with ovulation? The answer is not that there were not enough sperm in the right place. Rather, the reason is because the egg, or the sperm, or the combination of the egg and sperm has a defect of some kind (probably genetic) that prevents development of a normal embryo.

The bottom line is that you can use whatever position you like and you do not need to worry that it will change your chances of getting pregnant.