Age of gestation (size) at embryonic demise: tailoring counseling for lethal versus potentially viable aneuploidy.

The incidence of chromosomal abnormalities in spontaneous abortions is much higher than commonly appreciated. Using postmortem chorionic villus sampling (as we have previously described), our much increased yield of results allows us to divide embryos into two groups based upon potential viability. Embryonic size at the time of demise correlated with viability, i.e., the more 'viable' the embryo for term survival. Even in the absence of chromosomal results, the size of the embryonic pole can be used to infer, to a degree, the type of abnormality.