I have just received my 12 week NT results. Trisomy 21 was 1:893 so counted as low risk. It's a little concerning considering 2yrs ago when I was pregnant it was 1:9000. My OB says she isn't worried but we can do the harmony test for piece of mind. It's $425 for that piece of mind but if my OB isn't worried at all is it needed? Not sure what to do.