How much can pre implantation testing really tell you?

[Anonymous]

We did 1 cycle of IVF (after failed IUIs) and ended up with 3 blasts. One is now my 11 month old DC. I spent my entire pregnancy with her worrying about possible problems with the baby, which I realize is not unusual with infertile pregnant women. As we consider trying for another child with the remaining embryos, I wanted to ask what the latest news is on pre implantation testing, and how much they can really tell. I was 39 when we did the IVF, FYI, so I do worry about chromosomal and other possible disorders. We did not do any testing prior to my pregnancy with DC but I would strongly consider it next time unless there are downsides.