This happened to me- after a high risk of Downs Syndrome at a relatively young age, I had a CVS and got the all clear for the 3 main trisomies. All scans were clear although I continued to worry. My baby appeared healthy at birth but at 3 months it started to become clear he was not developing as he should and he does have a very serious genetic condition that would not have been picked up by routine tests. I always wonder whether the high risk (bloods, not nuchal) indicated our particular problem. Any others experienced similar? The medical line is that they are not necessarily linked.