Hello dear I understand your concern If precum goes close tot the vaginal intoitus then there may be chance of the pregnancy. But you have given I pill with in one hour of sex. It is highly effective in preventing the pregnancy. It has 95-97% success rate to prevent the pregnancy. So very less chance of the pregnancy (0-5%). But I pill cause change in the menstrual cycle as it cause hormonal imbalance. It may cause early period, delayed period by 1-2 week, excessive bleeding and intermenstural bleeding. If period will delay by the more than 2 week then go for urine pregnancy test and or blood HCG to confirm the pregnancy. If pregnancy will be there then still you can terminate the intrauterine pregnancy by the abortion pill under the supervision of the gynecologist. Meanwhile avoid stress, take healthy diet, drink plenty o water, maintain proper pelvic hygiene, and do regular exercise. Use condom in future to prevent unwanted pregnancy. Hope this may help you Contact HCM for further health query Best regards Dr. Sagar