Ok, I have done two IVF/ICSI (injecting the sperm into the egg), so lets see if I can answer some questions...
Just because you have IVF, does not mean you have the need for an amnio any more than the general population. Depends on your reason for doing the IVF. If you have genetic issues (family historys of genetic problems or genetic problems that are inconsistent with being able to fertilize an egg or continue growing an embryo, downs, trisomy 18, etc) then you would be more likely to have an amnio, if you so chose. Alot of time, when you do an IVF and have genetic issues you can do pregenetic testing. They can take one cell of an embryo and test it before transferring it back to the uterus, making an amnio less necessary. otherwise, an IVF pregnancy is treated as a regular pregnancy and it in itself does not elevate a pregnancy to high risk.
IVF does NOT mean that you did not use each spouses egg/sperm. My husband and I both did. It depends again why you are doing IVF. I didn't ovulate, but my eggs are fine, so we just bypass the ovulation issue with ivf. Donor comes in when woman does not produce eggs or are not a good quality or when a man has no sperm or his sperm cannot fertilize an egg, or neither can conceive and both are donated or embryos themselves are donated.
Hope that cleared it up some....
ETA:
(Not that it relates to the case, but just an interesting tidbit)
Madeleine and the twins could have even been created during the same IVF. If there were left over embryos from Madeliene's ivf, they could have been frozen and used to conceive the twins. They would be no more than siblings and DNA no more similar, just a interesting dynamic of IVF.
