If you look for information about the miscarriage risk from amniocentesis, the risk of 1 in 200 or around 0.5 percent gets repeated again and again. Examples:
However, they never seem to cite a source. I am looking for a semi-current study (let's say from the last 15 years, to account for current physician training and equipment) reporting the risks of amniocentesis.
What I am looking for would also need to have a control group - one of my problems with the above mentioned sources is that while spontaneous second trimester miscarriages are a lot less likely than first trimester ones, they do occur, even without amniocentesis.