Hi, Welcome to Health Care Magic. I am Dr Ramadevi Wani. I appreciate your concerns. Ipill taken within 24 hours of unprotected sex is effective in preventing 95% of pregnancies. So relax. If your girlfriend has regular menstrual cycles of 26-30 days, then the first and the last week of her menstrual cycle are safe period. If you have had sex during this time then there is no possibility of pregnancy. You can just stop worrying about it. Please note that the stress itself can delay the period. Due to the small possibility of method failure, If she misses her period, you need to get the pregnancy test done. I have an advise for you. If you wish to avoid pregnancy in future let your girl friend use reliable contraception like birth control pills or intrauterine contraceptive devise as they are more effective than emergency contraception in preventing pregnancy. In addition please use barrier contraceptive methods to protect yourself from sexually transmitted diseases. I hope this is helpful. If you have any further concerns do contact me through Healthcare Magic. Best wishes, Dr Rama