'I can't get pregnant if he pulls out.
Not true. Pulling out, also known as withdrawal, means that a man pulls his penis out of the vagina before he "comes" to keep sperm from joining egg. It is only 81 percent-96 percent effective in preventing pregnancy. Pregnancy can happen even if the guy pulls out, if he doesn't ejaculate, or doesn't put his penis all the way in. Here's why: when a guy gets aroused, he produces a fluid called pre-ejaculate ("pre-cum"), which can contain sperm — particularly if he's had sex or masturbated earlier in the last couple of days. When the fluid leaks from the penis before a guy comes, it can cause pregnancy.
Pulling out is not a very reliable method for young people because some guys lack the experience and self-control to pull out in time, or they say they will pull out, and then they get so excited and carried away that they don't. Also, some guys can't tell when they are going to ejaculate. '
I know that this is a very crude way of using statistics but....... that would mean that if 100 people use this method, around 4 to 19 of them would become pregnant. Just imagine if you have sex 100 times..........
LINK
http://www.teenwire.com/index.asp?taStrona=http://www.teenwire.com/sexeducation/wh_001.asp
I agree that the pull-out method is as valid a contraceptive method as condoms and the pill etc. However, it has the highest chance of failure out of all the other methods.
But disease aspect aside, its your body and your choice so i guess whatever works for you is cool