Okay, pre-ejac does not contain sperm unless there was a previous full ejaculation where there was not urination after (Im acutally educated...paid for university educated on this subject). Pre-ejac is there to clean out the tract in prep for semen, so it will not get you preggers all by itself. If he does not pull out in time (which most dont), or jerked off right before he was with you, then there can be a problem