Sitting on a bed sheet with semen on it without underwear will not lead to pregnancy. Because there is no substantial sexual intercourse between the man and the woman, not to mention no internal ejaculation, the sperm can’t combine with the egg to form a fertilized egg, so it won’t lead to pregnancy. Moreover, the survival of the sperm needs a certain temperature and humidity, when the sperm leaves the vagina or prostate, its survival time will become very short, the sperm’s vitality will also slowly decline with the passage of time, in addition to the semen on the bed sheet basically does not exist in the ability to swim into the women’s vagina and the uterine cavity, and therefore can’t be and the egg combined into a fertilized egg and pregnancy.