My girlfriend and I had unprotected sex on Sunday at 8 pm. She took Plan B One Step 1 hour later at 9 pm. She is due to ovulate on this coming Friday (5 days after we had unprotected sex.) I've read that plan B only stays in your system for 72 hours so is it true that the Plan B taken on Sunday night won't beable to to prevent/delay her ovulation (if it comes on Friday) because that's 5 days later. And sperm can survive for 5 days so she could still get pregnant. I also want to know if should take Plan B again before Friday.