What are the chances of getting pregnant by pre cum?

Possible: But not highly likely. Sperm are present and it only takes one, but they are not in high concentration. Consider a spermicidal lubricant, or better yet, condoms, in future to be safer from unwanted pregnancy and std risk.

Variable: Most studies have shown low levels of sperm or no sperm in pre-ejaculate with sperm not being motile (however, don't know how promptly samples were examined). One small study published in 2011 showed that there are some individuals with a high motile sperm count in pre-ejaculate. See: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564677/

Semen: There are sperm in these secretions, so pregnancy is possible. Use a condom.

Possible: It is possible. Depends on number of sperm in fluid and other variables.