Why am I measuring 11 weeks instead of 12 ?? UGHHH

 So I went to have my  nuchal translucency test today..and everything was  looking great. I was then told that I wasnt the 12  weeks 2 days that I had originally thought.  Baby was measuring 11 weeks 1 day.  So I was then concerned that the test was performed too early (I specifically made appt during 12th week b/c I didnt want it done in the 11 week..thought it was too early...anyway I was told everything looked fine..and the test is completley accurate at 11 weeks 1 day.  Then, I was asked if I was sure of when my last period (which Im 100% certain) was August  25th.  

I told DH in the room I think its b/c I know I ovulated much later in my cycle..like day 22.  So whenever I plug in my dates to  the computer the estimated conception is always off by a week.   Could this be the reason for the mix-up?   

The Dh asked me why cant it be that the baby is just measuring small?  I have no idea????

I don't know why baby would measure small, but you can get some comfort from the good NT results.  With my last child, I had my NT done at exactly 11w1d and was told the results would be very accurate.  He is now a healthy 21 month old.  

 Ok..thanks..that is comforting. :)

AnnaG1:

I told DH in the room I think its b/c I know I ovulated much later in my cycle..like day 22.  So whenever I plug in my dates to  the computer the estimated conception is always off by a week.   Could this be the reason for the mix-up?   

I'm sure that's a big part of the reason. The Dr. is basing your EDD off of a 28 day cycle w/day 14 ovulation. So, if you vary from that, you can adjust your dates accordingly. Some Dr's will take your dates into consideration, others will just go by their 'dating wheel' and not worry about it. But, if you do the math, you can see that Oing on CD 22 vs. CD 14 accounts for an 8 day discrepancy which is pretty much exactly what the difference is in the measurements by U/S. Also, at this gestation, the Dr. should be using u/s measurements as a more accurate method of dating and LMP.  

Tropical_coconut:

remember ultrasounds are never exact. My OB give a 7 day "grace period" with measuring..

Really? Every Dr, MW and tech I've ever had (I'm on my 5th pregnancy) has told me u/s for dating purposes are EXTREMELY reliable in the first trimester. Later on, when measuring weight, etc. they get less reliable, but I've had numerous medical professionals tell me that today's u/s are w/in a day when used during the 1st trimester.

I've never had an OB tell me the are extremely accurate infact I just has an ultrasound monday and they told me my baby was 5lbs 6oz and that it can be off by at least 13 oz give or take were their exact words (this is my second pregnancy i had a late term miscarriage previously) and yes the farther u get the much more less reliable they are

 I also go to a Maternal Fetal High Risk and they also have a 7 day grace period on ultrasounds. My first ultrasound I was three days behind, then my next I was ahead by 5 days and since then she's NEVER been on. I was on fertility drugs and knew exactly when I ovulated and when I concieved and they still wouldn't date me right. Infact they changed my due date twice in the first trimester based on ultrasounds.

. I just don't think medical science can be that accurate. My gf's baby was taken early cause they said the baby was only gonna be 3 lbs full term so they induced at 35 weeks for fear of growth problems.. The baby was almost 6 lbs....to me thats not even close to accurate

Tropical_coconut:

I've never had an OB tell me the are extremely accurate infact I just has an ultrasound monday and they told me my baby was 5lbs 6oz and that it can be off by at least 13 oz give or take were their exact words (this is my second pregnancy i had a late term miscarriage previously) and yes the farther u get the much more less reliable they are

Tropical_coconut:

. I just don't think medical science can be that accurate. My gf's baby was taken early cause they said the baby was only gonna be 3 lbs full term so they induced at 35 weeks for fear of growth problems.. The baby was almost 6 lbs....to me thats not even close to accurate

I specifically mentioned 1st trimester u/s for dating purposes because those are the only type of u/s that I've been told are extremely accurate. Once you're out of the 1st trimester, many babies take on different growth curves, it's harder to get their measurements, etc. Again, my comment was *specifically* related to u/s in the 1st trimester and I've asked this question at my MW/OB office (2 different practices), at the hospital for an emergency u/s and at the MFM I see this pregnancy as well. They have ALL said that it's extremely accurate early on and I think, truly, in the OP's case, her U/s is more accurate than her other dates based upon the situation she described w/ovulation on CD 22. This is really what makes the most logical sense.