I'm not sure exactly of the details of what you are planning to do or what your docs have suggested, but I did hear an awful story recently about a woman who was pressured to get amnio and didn't want it. She told her docs she wasn't terminating and didn't want to deal with the risks, but they really pressured her into it.
It reminded me of an article a few years ago that suggested there is evidence that some doctors, either due to training culture or bad financial incentive (i.e. they own the testing center), push patients towards tests they don't need. The article was required reading in the White House by the Obama administration before the healthcare bill, and my Republican father also liked it. Here's the link:
http://www.newyorker.com/reporting/2009/06/01/090601fa_fa...
Accuracy of Amnio:
I agree with the other posters that Mimi's post is wrong about the accuracy of amnio. Amnio is very accurate; most of the things it measures for are related to chromosomes, and with amniotic fluid, the docs can look at the chromosomes. The agenda is concerning here - many people who are against abortion feel that terminating a pregnancy due to a birth defect is modern day eugenics. I won't get into whether that is right or wrong, but I strongly feel every woman has a right to decide whether they want to terminate a pregnancy and what tests they get to determine the health of the fetus, even if her reasons don't comport with someone else's version of morality. I don't like the idea of women in China terminating when they find out they are having a girl; this actually upsets me a lot more than someone terminating for Down's Syndrome.
Risk of Miscarriage with Amnio:
The risk rates for amnio causing miscarriage are harder to figure out. I heard about the 1 in 1600 number, made me feel better, but it was from a study that had some methodology problems. (I think it only took place at one hospital, and the process of studying something changes it, yada, yada.) However, the old statistic of .05% (1 in 200) is from a study in the '70s from before they were using ultrasound with amnio. Its kind of difficult to make a perfect study to show the affect of amnio on miscarriage, but from what I've read, the recent literature indicates that if it is being done in a hospital or modern medical center with a high-risk pregnancy doctor, the miscarriage rates are much lower. I believe there was a German study in 2008 that looked at general miscarriage rates with amnio in several different settings. I haven't read it yet, but ultimately, I think its irrelevant to one woman's individual decision, because she should figure out the situation where she is getting amnio done.