The 1st day of my wife's LMP was July 18. She then stopped taking Yasmin birth control pills around July 24. She started bleeding again around August 1. We found out she was pregnant around September 8. According to 1st ultrasound, baby was 8 weeks old and EDD was May 20, 2008. Then, according to 2nd ultrasound a month or so later, baby was 14 weeks old and EDD is May 11, 2008. Shouldn't the EDD be about 2.5 weeks earlier, like around April 23, 2008, since the 1st day of her LMP was July 18? If the EDD is correct, then her LMP was actually around August 5 but she was not having a period then!!!! We are really confused. Please help!!!