conception date concern

At my last ultrasound my dr estimated my due date to be July 25,2012...I unfortunately had two seperate sexual encounters, the first on Oct 2nd and the second on Oct 30th. Can anyone say for sure which is the date of conception? I can't remember my last menstrual cycle :-/ If I did conceive on the 30th how can I know for sure so I can stop worrying? Ive looked at conception calendars, but how accurate are they? Was their enough time between the 2 dates to get a 100% accurate answer? I should also note that during the Oct 2nd encounter, he did not ejaculate (other than precum of course). I took a pregnancy test November 10th and it was negative, however, I took another @ home pt on November 16th which then was positive. I've had 3 ultrasounds all confirming the same due date. I realize a dna test is the only way to know for sure and their will be one performed, I'd just like to have a heads up as to what you guys think so I will know what to expect. I should also note that I am now 34w 6d and have been having BH contractions frequently...usually at least 25-30 mins apart, not painful and usually do not last but 45-60 seconds. This is also my second child. I hope I have all the info you need. Thanks in advance!

[Elaine Brown, MD]

A due date of July puts your date of conception on November 2(which is totally possible with an encounter on October 30th).  If you had a first trimester  trans vaginal ultasound, it should be accurate within 3-5 days and should rule out the first partner with fairly good confidence.  Second trimester ultrasounds are less accurate with a possible error of up to two weeks.  That still should rule out the first partner with reasonable certainty.
Hope this helps!
Dr B

[rosebleed]

I'd say October 30th... Only reason I say that is because I'm due mid August and conceived late November! Sperm can only live up to 5days in the best conditions, so I would rule out the first date... Either way probably best to get a DNA test done if your real worried. :) good luck!

[tiny321]

Yes oct 30 because I conceive nov 2 and due july 27

[naryashadow]

I think it'd be Oct 30 too because I'm due on the 24th which has my conceiving at Nov 1 but the last time I had had sex with my husband was Oct 28th and nothing else until Nov 15 due to the stresses of work and just plain being worn out. If it were the first one, you'd probably be due a lot sooner.

[Chica17]

Im in a similar situation I had two partners in november one the 11th then the othr on november 17th.,i came on my period after the 11th and my due is august 11th but the calculator says I concieved the 19th. I dnt know which one is the father. I need help to understand.

[ladieemundy]

The one for 30th