Condom forward movement may result in pregnancy if semen overflows; if there is no semen overflow it may not result in pregnancy, so observation is recommended. The condom moves forward more, after ejaculation, semen is easy to overflow from the condom, if it enters the vagina, sperm and egg combination, it is easy to cause unwanted pregnancy. In addition, the condom forward, exposing part of the penis and vaginal mucosa contact, semen into the vagina, but also easy to cause sexually transmitted diseases. Therefore, choose a condom model that suits the thickness of your penis, and observe whether the condom slips off during intercourse. If it is detached from the root of the penis, you should stop intercourse and adjust the condom. If the condom moves forward and semen spills out, you can take emergency contraceptive pills, such as levonorgestrel tablets, as prescribed by your doctor after intercourse to help prevent pregnancy.