Condoms and the withdrawal method are, according to the newest study by Contraceptive magazine, are both found to be about 60% effective with regular usage, and 75% with perfect usage. Unfortunately, it is rare to have perfect timing with the withdrawal method. I'm sure that I don't have to point out how low those rates are when you consider that most people have sex about 190 times a year.
Just in case, I will. That means that if you have sex 190 times a year, about 42 times you're method of birth control is probable to fail.
Combined with birth control or the rhythm method, though, that changes.
Ultimately, though, if you're wanting a safe way to have sex without a condom (which is only safe if you have a verifiable copy of his STD check, really) you need to get on the pill or something.
It's not as safe, no. You have more risk from that than from using condoms. Of course, it's a very small risk. People always tend to blow it out of proportion. Pre come can get you pregnant, it's true, but it probably will not, unless you are both exceedingly fertile. Add to that the fact that there is only a small window each month where you could get pregnant anyway, and you're probably not going to get pregnant that way.