So I am currently 15 weeks and 2 days pregnant. My due date is December 3, 2014. On the week of January 10-14th I was separated from my husband and slept with someone else, wearing no protection. A few days before my period that month I took a pregnancy test that showed negative. I then got my period when I normally get it but it was shorter then normal which I thought was strange because my period is very consistent with date/Length of period. I thought it was weird but didn't think much of it. The end of February came and I got my period like normal on Feb 28th, normal length of days. End of March comes and I missed my period, took a pregnancy test and I come to find out I am pregnant. I have only had one ultrasound so far at 8 weeks and 4 days and they told me I was at 9 weeks (3 days off). I am wondering is it possible for a ultrasound to be 2 months off? I only slept with this other person that once and have been back with my husband all of February and March. Should I be concerned? Or are Ultrasounds pretty accurate?

They aren't precise to the day but they also aren't off by 2 months.

Thanks

You NEED to have DNA tests run after the child's birth... there is no other way to be certain who the father is. And you do need to know for a number of reasons. Medical history is only one.

Your ultrasound at 8 weeks would have been pretty accurate. This is because development is fairly precise in the early weeks... for example, what can be seen at 6 weeks will be quite different from what is seen at 8 weeks. If you had become pregnant from the encounter in January, your due date would be in October.

They can not be off by two months.

With that said, a pregnancy test done two days from period will not show proper, so of course it showed negative. Lots of issues here.

It does not seem possible, but they go by what information they are given.

But if I was pregnant by the first person. I would 23 weeks right now. I don't look 23 weeks. And I would think there would be a major difference on the ultrasound for a 2 month difference. Right?

Yes, there would be a significant change from 15 weeks to 23 weeks on an ultrasound. Ultrasounds, particularly early ultrasounds, are quite accurate. Usually up to a 2 week difference, not a 2 month difference.

When I went to the ultrasound and I was 9 weeks. That would mean if It was from the 1st person I would have been 17 weeks. A 9week baby and a 17week baby, it just seems like they would have noticed major differences.

You are correct. There would have been major changes between 9 weeks and 17 weeks. It is safe to assume that your husband is the father of this child.

With an EDC of 12/3/14, you most likely conceived on or around March 12. You can stop beating yourself up over who is most likely the father of this child, as it would appear to be your husband.

I understand the responses you have received so far have placed you in panic mode. If you wish to take a DNA test to ease your mind, that is okay. Rest assured that the difference in dating is so far off as to remove the one night stand from the equation.

Thank you... I know the chances are slim.. I think the guilt is just eating me alive.. Thanks for all your help!