Dr. Sawyer: There is a possibility that pre-ejaculatory fluid (posh name for ‘precum’) may contain live sperm from the last time a man ejaculated, so if the man’s playing Russian roulette with pregnancy by using the pull out method, there is a chance that his hookup may be pregnant by about the time he actually withdraws. The lifespan of sperm once it passes the ejaculatory ducts is about 72 hours, so very theoretically, if the man hasn’t ejaculated for about three days, then very theortically, there may be no live sperm in evidence. But really …. how many college men haven’t ejaculated in the past three days? Moot point!