I'm having identical twin boys. At 12+3 I had NT screening and it was 1.6mm and they said it looked fine however one twin refused too cooperate and they decided too do a quad test for just Down's syndrome. It came back 1:57 ... however I'm diabetic and I'm on medication. They have too put that into consideration and they got that a little wrong. They also weighed me much lighter than I am. I'm scared.