Baby measuring small on US?....LONG

brandi_07

Hello everyone!!  I have a question, but I will do a quick intro first.  I have been married to my DH for 5 years and we have a 2 year old DS.  I got my BFP on 8/27, the day before my period was due.  So here is my question...

I had my first US yesterday with the dr and he was unable to find anything in the sac and said he thought I was having a "failed pregnancy".  He gave me a few options and said I got just wait (b/c he thought I would start bleeding soon), get a HCG quant, or another US at another place in case he missed something.  I told them I wanted labs and another US.  So we went to the other place and got the US and they immediately found the baby and the HR at 126, but she said I am only measuring 5w5d, when by my LMP I should be 7w1d. 

I know that you can ovulate late, but I got a positive OPK on 8/16 (CD16) and got my positive preg test on 8/27.  So that means that I would have just conceived within days and got a positive.  The office says they think everything is fine and I am wrong with my dates.  But I requested another US, so in 2 weeks I am going back. 

I guess my question is...what can it mean if the baby is not measuring right/growing at the right speed?  Possible M/C? Or is this normal?