I went for my 18 week US yesterday... I was supposed to be 17w6d yesterday. It was booked a bit early because of holidays and we were warned that baby may be too small up front. (I have never used this US facility before and all my others were done at another place) When she took the first measurements baby came up measuring 16w 2d which is impossible. I can account for 4 days because I ovulate 4 days late. I know when my last LMP was absolutely. Also we had a NT scan that only put us the 4 days that I already know I am out. I had a gender scan 3 weeks ago that told us the sex and this would not have been possible if baby was so small. Baby seems to have slowed down in the last 3 weeks and we are going nuts here trying to figure out why. Just wondering if there are any ladies this has happened to and what the outcomes were? We have another scan on Jan 12th and im really hoping baby is just measuring small. The measurements all come up as symetrical but baby is still not on the charts. 
