What are the chances of getting pregnant of precum ?

Rare, but possible. : Results of research on whether precum contains sperm is somewhat sparse and mixed. General consensus is: 1) in most, but not all, men, precum contains no sperm; 2) precum most likely to contain sperm if there has been a recent previous ejaculation and no urination to "flush out" residual sperm/semen in the urethra; and 3) when sperm present, it is in low concentration making pregnancy unlikely.

Significant: recent studies have showed low levels of sperm (and sometimes no sperm) in pre-ejaculate. One study showed that there are some individuals with a high sperm count in pre-ejaculate.

Low, very low unless: You happen to be the one in a gazillion who gets pregnant and then, you're going to think the guy who came up with the statistic is the worst probabilist on the planet. Be a lot easier on your psyche if you just make him use a condom. No such thing as a guy who promises to pull out IN TIME! Not one exists in the universe!

Honestly? unknown: It is fair and reasonable to believe that pregnancy can occur for pre-cum - I believe it - so the chance is "yes" it can happen. No one can give you a number (percent) because not surprisingly, it has not been studied.

High: During fertile period. Will not state the exact percentage as that will be irrelevant. It contains life sperm capable of fertilizing a willing egg

Sperm: it takes but one sperm to fertilize an egg. There are plenty of sperm in the pre-ejaculatory se creations of the penis. Therefore, if the sperm got in the vagina you could get pregnant. In simple terms: penis + vagina - birth control = pregnancy.