Expert: Dorothy H, LCCE - 7/29/2011

Question
Hi, I'm super confused about the whole lmp/ultrasound dates and I really need help since I've been constantly stressed about my situation.
My lmp was 03 april 2011, according to that my EDD is 10 jan 2012 which according to that makes me 16 weeks 5 days today, I had
early ultrasound on may 16 that measured 5 weeks 3 days(according to the doc it changed my EDD to 12 jan 2012), and another ultrasound
on may 23 that said 6 weeks 6 days(which measured back to the original date of 10 january) Here's my problem that's been worrying me like
crazy, me and my current boyfriend were on and off most of the month of march, on march 22 I made a mistake by hooking up with a guy at
around 1 am that day(using the withdrawal method) after that me and my boyfriend got together again and always had a strong sexual relationship
and never used protection other than the withdrawal method. I got my period on time as usual and after my current boyfriend has been my only
sexual partner, I'm just wondering if there is any possible way that the other guy could be the father? or if my boyfriend is?, I'm so worried
cause I made the awful mistake and I want my boyfriend to be the father 100%. These dates confuse me and make my stress and worry a lot worse.


I'm just hoping you can give me advice or make this whole date thing more clear to me, and if there is a possible way that you can help me figure this
situation out, thanks.

Answer
Even with the two different due dates, it's clear that you got pregnant in mid to late April.  There is no way that you got pregnant from sex on March 22, especially with all those ultrasounds.  Two days difference in the ultrasounds is a normal variation; whichever one of them is correct, it still would be impossible for you to have gotten pregnant in March.  If you had gotten pregnant in March, the ultrasound results would have been much different.