How accurate are dating ultrasounds at 6 weeks?

[CSA11]

Hi, my situation is rather complicated. I don't want to sound like a jerry springer episode, however to the average joe it may sound that way. I am just wondering how accurate a dating ultrasound is at 6 weeks....I had one done at 6 weeks 5 days and another one at about 7 weeks. The one at 7 weeks was off from the first one by 4 days. I am in college just living the good life and I had two partners, 1 whom I had been sleeping with unprotected for about 2 years and my ex who I slep with once since we broke up over 3 years ago. Both I slept with, within exactly 7 days apart. So please help! I am freakig out and just want to know if an ultrasound can be off by a week??? Either way I never thought I could get pregnant so I am keeping my baby regurdless, I would just like to put my mind at ease.

[CharChar85]

You ovulate around 14 days after the first day of you period(assuming that you have a 28 day cycle). Sperm can survive for up to 5 days. I think it is pretty unlikely that you got pregnant from sex on the first day of your period. Thats just my opinion though. Good luck!

[ntombizimceluxolo]

I need to know the possibilities: on the 1st dec I started my periods and had unprotected sex with one of my boyfriends then on the 10th dec I had unprotected sex again with my other boyfriend. At 6 weeks I found out I was pregnant however the doctor said I would have had sex on the 7th dec which is impossible because I never had sex on that day. My delivery date was 5 Sept however as time progressed my delivery date changed to 12/13 Sept but the doctor said its only because the feotus was getting bigger.

My question is what is the posibility that I got pregnant when I had sex during my periods or would I have gotten pregnant from my second boyfriend. This whole thing confuses ne because would his sperm have survived this long to inpregnate me during my periods or should I just believe that my second boyfriend is da father and that the 6 weeks scan did not give a true reflection.
I will be doing a dna test for peace of mind however I just needed to get clarity before I run a test on both fathers whereas I can just do it on the one and save cost.

Please help!!

[skheavner]

My 6 week ultrasounds have ALWAYS been wrong.  My first daughter was 2 weeks off and so was my second one.  The first was two weeks early(so they said I was 6 weeks when I was really 4) and the second one was late(they said I was 6 weeks when I was really 8).  Most ultrasounds have a + or - on them, so it will read 8 weeks + or - 4 days or 3 days or 7 days.  So that means that they are admitting it can be a few days off.  But in all actuality it can be even more than a few day off.  Every woman ovulates differently.  What the above user said is true for many women but not all.  I ovulate at more like 7 days before my period.  But I do have to say that it seems like it is your ex who impregnated you just because if you have been sleeping with the same guy for 2 years w/o protection and haven't go pregnant it could be his sperm.  I know that with my husband, both times we wanted to get  pregnant it took a few months just because of how his and my body work together... Hope this helps

[MrsPincince]

Ultra sounds are pretty accurate. One thing that can help u figure when u conceived is this: Most women ovulate 14 days BEFORE their expected period. U can count 14 days back from the day u were supposed to get ur period and that will narrow it. If u slept with them 7 days apart it should be fairly simple to figure out who's baby it is. Otherwise u'll have to be upfront and honest with both  of them and wait for a paternity test!!! Good luck:)