Conception

[butterfly33664]

My due date is 8/26/2014 w/ my LMP on 11/13/13. I have used a few of the conception date calendars online and have put in my LMP & it says my due date should be 8/20/2014 which is only 6 days off but anyways. i made a mistake on 12/11/13 & need to make sure there is no way i conceived that day?

[AnnieBrooke]

Never a bad idea.  The facts in your case don't call for one, but there is something to be said for no longer worrying.

[Greenandblue2013]

I think I'm going to need to take a DNA test, I'm so petrified :(

[AnnieBrooke]

Your ultrasound uses the medical method of counting pregnancy, which is to say the "gestational age" count that begins with the first day of your last period, not an assumed date of conception. Your doctor also uses that count.  If a doctor tells you that you're 11 weeks pregnant, it means you're 9 weeks from the assumed date of conception.

The pregnancy did not result from the 8th of December or the 2nd of December or any date in early December.  Here is what the conception calculator says for the due date of September 25:

     First day of last menstrual period:  December 19
     Probable date of ovulation:  January 2
     Possible dates of conception:  December 29 to January 6
     Due date:  September 25 (40 weeks)

[Greenandblue2013]

If sperm survived up until the 8th of December (and a pregnancy resulted) would they have then added two weeks onto that date to get the LMP for dating the pregnancy?
I just have a thought that if it did survive up until the 8th then there technically would only be 18 days between when my ultrasound says I conceived and when I could have potentially conceived with the other guy and I didn't think that would be a large enough gap to determine who lithe father is?

[AnnieBrooke]

Your current partner.  The guy on the 2nd of December would be far too early to have gotten you pregnant if your due date by ultrasound is September 25.

[Greenandblue2013]

I had sex on the 2nd dec with an unknown man, I had what I believed to be a period on the 19th dec and was then having sex from roughly the 24th dec - 15th jan with my current partner.
My due date was given to me at my. 9+6days ultrasound giving a due date of the 25th September. I also had an ultrasound at 11 and 12 weeks which confirmed this date

Who is the father

[AnnieBrooke]

Yes, it's possible to conceive the day your period is supposed to come, because sometimes periods don't come when expected.  Periods can vary in relation to ovulation, and in fact it sounds like yours did.  Don't count or assess based on your period, judge from the ultrasound, and count backwards 266 days from the estimated due date they gave you.  This holds true even if your period doesn't line up -- the ultrasound saw and measured the actual embryo, and it trumps any info about the first day of your last period.

The conception calculator gives the following for the due date of August 26.

     Probable Date of Ovulation:  December 3
     Possible Dates of Conception:  November 29 to December 7
     Due Date:  August 26 (40 weeks)

As I said, it sounds like you were already pregnant by the 11th.  I wouldn't be too worried, it's just not a bad idea to get a DNA test once the baby is born because it puts all questions to rest forever.

[butterfly33664]

Because that was the only time it happened & that was the day i was supposed to of started.

[butterfly33664]

Is it possible to conceive the day you are supposed to start your period?

[AnnieBrooke]

In such a situation, with the margins for safety being a little slim, I definitely recommend you have a DNA test done once the baby is born, just to put the question entirely to rest.  If you can't admit to one guy what happened, test with the other.

[butterfly33664]

I also had a blood test done on 12/30/13 & the results came back the next day & they said that i was six weeks. Everytime i look at it, from different ways, it wouldn't be possible but i wanted someone else's input to see what they thought. I know they do somewhat go by your LMP & w/ an ultrasound, but i just figured my due date would be no later than 8/21/14.

[AnnieBrooke]

It does sound like you were already pregnant by the 11th.  Your conception window based on your due date is November 29 to December 7.  If you were to try to compute from your period instead of from the ultrasound (which is never a good idea), it would put the window even further back.  

[butterfly33664]

My menstrual cycle is usally every 28 days so from my LMP on 11/13/13 that would put me starting again on 12/11/13 which is the day i was with the other guy. i took a home pregnancy test exactly 2 weeks & 1 day from the day it happened and 2 very dark lines showed up almost immediately.

[butterfly33664]

I got my due date from an 8 week ultrasound.

[AnnieBrooke]

Hi, butterfly, how did you get your due date, was it from an early ultrasound?