How accurate is early ultrasound?

[lel1985]

Hi, I am 20 weeks pregnant currently. I had unprotected sex with someone other than my husband on 2/15/10. I had a light period that was latert than normal on 2/25/10, then another on 3/25/10. My husband and I had sex on 4/4/10 & 4/8/10, he "pulled out" both times, so I was shocked when I found out I was pregnant in early may. The dr. did an ultrasound on 5/13/10, 6weeks 4days pregnant, due date 1/3/11. Ultrasound 5/27 says 8weeks 4 days. I had another u/s at 17 weeks and it was a few days ahead, due date 12/30/10. Is it possible i could have conceived back in February and the ultrasounds are 6-7weeks off? Or can I be absolutely certain my husband is the father?

[lel1985]

Thanks! I had 2 full periods in between, and my doctor assured me I conceived in early April and it was impossible to have conceived in February, but I wanted a second opinion! My husband and I were separated at the time and we are back together now that we are expecting, and we are very happy, so I do not want to be stressed about this! Thanks for the answers!

[alaysha]

Its your husbands. If it was the other persons the due date would be closer to the beginning of November.

[shishka]

From all the dated above, your husband is the father.

[bhenneker]

Sorry I meant to say April, not May..

[SunWorshiper_26]

Really the only way to be completely sure is a DNA test. Sorry!

[shuga1109]

I don't think you start your pregnancy weeks on the day you conceived.  County back from the first day of your last period.  That's my understanding, but I could be wrong.  If I am incorrect, I apologize.  I don't believe your weeks begin on your ovulation day/conceiving date.  I belileve pregnancy starts on day 1 of your last real period.  Hope this helps you calculate.  If you are 20 weeks now, and you count back exactly 20 weeks, it takes you back to exactly March 25, 2010, which is the first day of your last period.  Your husband is most likely the father because ovulation would have taken place approximately 14 days after March 25th, which takes you to exactly April 8th, which you had sex on that date with your husband.  This is the date you would have most likely conceived.  Hope this helps, but I am no doctor.  Good luck.

[bhenneker]

Your husband is the father, as long as you never had sex with anyone else in may. Pull out method is NO kind of birth control.U/S can be a few days off but not months.