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Avatar universal

Please Help!

I had a one night stand April 27th, 2013 when me and my boyfriend got in a big fight. we got back together the next day and still are. Well, the doctor says I am 18 weeks and 6 days pregnant as of today from my ultrasound I had at 8 weeks. he did a crown to rump measurement of the fetus that day.  Before I even went to get an ultrasound, I went to a health clinic to have a pregnancy test and by my LMP, they told me I should've been almost 11 weeks when I got my ultrasound done. my due date was changed from January 18, 2014 to February 1, 2014. I am pretty I gave them the right LMP, or at least really close to being correct. I do have some long cycles but I never really kept up on them. how do I know who the father is? or atleast which one it most likely is. I need a second opinion. could the ultrasound be wrong by 2 weeks? is my LMP date what I should go by? I am freaking out and need answers please
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Avatar universal
Most doctors originally calculate your due date by the first day of your last known period which means at the time of conception your pregnancy is considered 2 weeks when the baby is conceived so that can explain the difference in due dates.
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
When you had the ultrasound at 8 weeks, was it 8 weeks and 0 days or 8 weeks and some other amount of days?  And did they give you an estimated due date that day?
Helpful - 0
Avatar universal
I cant remember exactly how many days. But yes they did give me a due date. February 1. The date of conception changed by a couple weeks since my due date changed at my ultrasound
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
For a due date of February 1, the conception calculator I use suggests the following.  It does not sound like sex on April 27 was anywhere near your ovulation.

     Due date:  February 1 (40 weeks)
     Probable date of ovulation:  May 11
     Possible dates of conception:  May 7 to 15

Helpful - 0
Avatar universal
So do you think i just ovulated really late and thats why my LMP is so off my conception date? Becuz by my LMP, it says i ovulated on april 27. But then my ultrasound was way different. Do you think the father was my boyfriend and not the one night stand guy?
Helpful - 0
Avatar universal
And the ultrasound should be accurate, especially if he said i was 8 weeks right? Is there any possibility it might be the other guys?
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Avatar universal
Also i think he might have told me i was 8 weeks and 6 days when he took my ultrasound.
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
It's hard to answer the question "So do you think i just ovulated really late and thats why my LMP is so off my conception date?" because you have not in fact said when your last period began.  You have said that your cycles are long, and that by your LMP you were a certain amount of weeks pregnant, and that by your LMP you should have ovulated on a certain date, but you haven't mentioned an actual date when your last period began.

An ultrasound in the eighth week is usually pretty accurate; at most the margin for error is considered to be +/- a couple of days.  I take it you are saying that you think there is a chance the sex with the wrong guy produced the baby because your last period came a couple of weeks before sex with him.  But you also say you have long cycles.  If the sex with him was on April 27 and the ultrasound says your likeliest day of ovulation was around May 11, all his sperm in your system would have been dead by May 1 or 2.
Helpful - 0
Avatar universal
My last LMP started around the 13 of April. Sorry! I thought i mentionsd that!
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Avatar universal
I just want to make sure theres no way the guy from April 27 is the father. And that the baby really was concieved sometime in may
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
I would go with an eighth week ultrasound over a projected ovulation date counted on a calendar, especially if I had long or irregular cycles.  But "I just want to make sure theres no way" is putting things very strongly.  Only a DNA test would be able to answer that question to that level of certainty.
Helpful - 0
Avatar universal
Thank you! That was very helpful. And i am getting a paternity test but i just want to know what the outcome is mostlikely going to be. So the ultrasound should be more accurate than the LMP date they went by at the health department when i took my pregnancy test?
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
Ultrasounds see and measure the actual embryo.  If they are early in the pregnancy, doctors use the measurement from the ultrasound if it conflicts with the woman's report of when her last period was.
Helpful - 0
Avatar universal
So pretty much there its not likely the baby could have been concieved in april at all
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
I would go with an eighth week ultrasound over a projected ovulation date counted on a calendar, especially if I had long or irregular cycles.  "Pretty much there is not likely" means what, about the same as "I just want to make sure there is no way"? :)
Helpful - 0
Avatar universal
Haha thank you! Im sorry i just want to know before the paternity test but i know its nit possible
Helpful - 0
Avatar universal
I just saw something online that calculates my pregnancy and it said that day 1 of my pregnancy was april 28... Thats with my due date of february 1.. So is it saying that it is a possibility that the guy i had with sex on april 27 could be the father? I know by the conception calendar for a due date of february 1 i conceived between may 7-11 but why is this website saying that my first day of pregnant was april 28?
Helpful - 0
134578 tn?1614729226
COMMUNITY LEADER
Day 1 of pregnancy, counted the medical way, is the first day of bleeding of your last period you had before getting pregnant.  We've already pretty much established that your long cycles make that number very iffy.  Go with the estimated ovulation date that you got from counting back from the due date.  Your front-end dates (when your period actually began and when the doctor's computer assumes it began) will be inaccurate if you have a long follicular cycle, which most people with long menstrual cycles do.  (That is the part of your cycle before ovulation.)  Work backward from the date they gave you that is based on the size of your baby, which is your estimated due date.
Helpful - 0
Avatar universal
Okay thank you! I was just curious since i saw that
Helpful - 0
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