I was under the impression that the fertlized eggs (pre-embryos) that were normal/healthy were the ones either implanted into the mother or saved for future use...not discarded. It makes no sense that they would just throw out ones that were 'good'. I do know that sometimes they implant more than one fertilized egg into the woman, but sometimes they don't survive, or only one will. In that case that isn't quite the same thing as deliberately killing a few fertilized eggs, if the mother was hoping that they would take and grow. But if I'm wrong about this, correct me.
Once they are frozen for a period of time they become no good to use and will be used to harvest the baby for parts in embryonic stem cell research. In England they are incinerated after three years, it's another Holocaust.
Before there is an embryo, there are gametes of the man and woman. The first cell division following conception is the proof that a new individual human life (if the gametes are human sex cells) is expressing his or her self direction and this is an individual at earliest embryo age, not a fertilized egg. The term 'pre-embryo' was created to confuse issues, to try and create an ambiguity regarding the newly expressing human individual, to allow the manipulators of these very young human beings to exploit their LIFE for experimentation and profit. Please stop using that false term when referring to human embryos, human concepti.