Does precum contain sperm? if the man has not ejuculated while your having sex?

Sperm: Yes sperm can be found in pre ejaculation fluid.

Potentially yes: 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/