Paternity Determination: Identifying the Father of Your Baby

Question
The first day of my LMP was 12/20/2009. I slept with my ex on 12/25/2009 and 01/01/2010. I also slept with my boyfriend on 01/03/2010 onwards. I went to my OB on Feb 15 and she told me that I am approximately 8weeks preggy. Then I had a transvaginal U/S on Feb 19 which gave me the result of 7weeks, 2days with a due date on Oct 6, 2010. With the following info, who do is most likely to be the father of my baby. Is it my ex or my recent bf? Please help, I'm so confused.

Answer
The 7 week ultrasound is going to be more accurate than going by your LMP. The ultrasound should be accurate within +/- 3 days.  Going by that, it puts conception around January 12, which points to your recent boyfriend as the father.

Dorothy H, LCCE