Pregnant and Confused???

[JaeMichelle91]

Ok ... 3 months after my bf and I broke up, I had sex with a ons.  My period was on 09/12/2013 and ended on 09/14/2013 ( which was the day I had sex with ons ). My bf and I got back together on 10/3/2013 and had sex that very same day. On 10/23/2013 I found out I was pregnant. The ultrasound and my lmp dates line right up with each other. This put my conception date around 09/26/2013, which is where I'm confused because I did not have sex with anyone around that time. Also, the first guys *** would have been gone by then, right? Is there any way I can pinpoint who the father is?

[JaeMichelle91]

I will, but it's just so nerve wrecking!!! I've never been in this type of situation before.

[AnnieBrooke]

Even the stretch between 9/14 and 9/26 is too long for sperm to survive.  I would still get a DNA test so you will never worry.

[JaeMichelle91]

Btw, currently 23w4d as of today and all ultrasounds I've had line up w/ my last period.

[JaeMichelle91]

Sorry, I got the date wrong. I had to go back to the ultrasound and saw that I was actually 17w6d on 1/15/14 but still I'm a little bit confused because my doc says that I would have concieved on 09/26/13 but the first guys sperm would have still been gone by then right?

[AnnieBrooke]

Well, if you counted September 29 as your conception date by counting back 17w6d from January 30, that is a false notion.  When the doctor says you're a certain amount pregnant, like 17 weeks or whatever, he or she is basing this on the assumed first day of your last period.  (Which, using 17 weeks 6 days count, would have been September 27.)  The medical way of counting pregnancy doesn't start on an (assumed) conception date, they don't have any way of seeing conception.  It begins on a (computed) first day of period, since that can be seen.  They then add two weeks after that date, and your conception would occur then.

Problem is, you had the ultrasound late enough that it could be up to a couple of weeks off.  The margin for error in using ultrasound measurements to calculate the conception date of the baby gets larger and larger as pregnancy progresses, since all embryos begin at the same size (one cell) but some can grow faster and some can grow more slowly than average.  So by the time you're in your 17th week, a doc would say "plus or minus a week or two" about dating the pregnancy with an ultrasound.  Which, based on the difference between when your period began and when the computations say it would have begun, it seems like you are.   (Off by a week or two.)  It doesn't quite go back as far as September 14, though, even with a pretty large margin for error.

If you were to assume that you could count from 17w6d and take that number to the bank (an assumption I hope you see can't be certain), you would have conceived on October 11.  Even counting back a couple of weeks or more, you still aren't in the range for the guy on September 14.

It seems most likely that the baby is your boyfriend's.  Get a DNA test to put the question to rest, it is only fair.  But the one night stand is pretty far out there and it is very unlikely you are pregnant by him.

[JaeMichelle91]

I wasn't able to get one until 1/30/2014 and at the time I was 17 wks 6 days.

[AnnieBrooke]

The ultrasound was how early in your pregnancy?  And what exactly did it say, it would not have given you a conception date but a number of weeks since the assumed first day of your last period or an estimated due date or both.