Question regarding date of actual conception-please help

Ladies this is from a friend; is this possible?
"Had blood test for pregnancy. Was told I was 6 weeks pregnant from results. 2 weeks later went for 1st checkup. Which would make me 8 weeks pregnant. 1st ultrasound on that visit...Dr. said I was 6 1/2 weeks. How can it be off that much?"
Ladies does this sound right, to be off by this much?! She is trying to find the window of actual conception which I always thought was @ 72 hours
thanks

Re: Question regarding date of actual conception-please help

i could be wrong but i don't think a blood test can tell you how far along you are. it measures levels (progesterone maybe?? don't know) and you want those levels to double every day or 2.

for ex----my friend just had blood work done and her levels were about 5 times mine even though we were at the same point (approx) in pregnancy when the blood was taken.

they usually date a pregnancy by LMP and then later by how the baby is measuring. then they adjust it accordingly if necessary.

Message edited 6/16/2009 10:07:56 PM.

Re: Question regarding date of actual conception-please help

I'm going through a hard time now because I am about 6 days off from when I had that 'oops' moment until what I was measuring last week when I had my sono. I knew I could be a couple of days...but not 6. Sono tech said sperm could likve 4/5 days and it could take 2 days to implant which is when you are actually "pregnant". I'll find out tomorrow with sono...so I'll let you know!

Re: Question regarding date of actual conception-please help

Thanks ladies!
She is very stressed over this as it may be a paternity issue

Re: Question regarding date of actual conception-please help

Sperm can live inside for 4 or 5 days before conception so yes, she could have had intercourse a week before she conceived and that person could be the father of the child.

Did you hear about the woman who had twins and one was fathered by her husband and the other was fathered by someone she had an affair with.

Re: Question regarding date of actual conception-please help

I would go by the sono dates. My doctor wouldn't even guess how pregnant I was by my first blood test. He said there is such a huge range that the numbers can only really just tell you 'yes or no'.

Re: Question regarding date of actual conception-please help

Re: Question regarding date of actual conception-please help

A blood test can give you a roundabout timeline. It won't be exact. I would go by the sono.

Re: Question regarding date of actual conception-please help

I honestly don't think a sono would even be accurate if paternity is an issue...

I pretty much know exactly when we conceived as I was tracking my ovulation & we were only able to do the deed once during the 2 weeks we were traveling for the holidays. Based on my last period & when I ovulated, I should have been 7 weeks at my 1st sono, but I only measured 5 1/2 weeks. At what should have been my 8 week sono I had caught up a bit, but was still measuring a week behind & I have been ever since. The doc said that I probably had a late implanter - which means that it took almost a full week for the fertilized egg to implant & really start growing...

Even when planned, it's not an exact science & if your friend was with one guy one week & another the next, either guy could be the father. Only a paternity test will tell. I'm so sorry that she's going through this - I imagine that it must be rough

Re: Question regarding date of actual conception-please help

I think sonos are the most accurate, and that's what I would rely on. Blood tests really cannot tell, because there is a very wide range of "normal" hormone levels at different times.

Was her cycle very regular? If she has been every 28 days for her whole life, it's pretty likely she conceived about 14-16 days into her cycle. If she is pretty regular, and her cycle and the sono give the same estimate, I think that's pretty reliable and I wouldn't be concerned about the blood test