This is inconclusive (at least regarding the birth control pill). There is no scientific evidence that it does prevent implantation of a fertilized egg (if I have been reading all of these information threads on the pill correctly). The scientific community only has to admit that it is possible, in the face of no evidence.
Tec---you are looking for an answer that is unavailable. But let me put it to you this way. YOU say there is no scientific evidence that these methods prevent implantation. WE DO know that it is a strong possiblity---because that is how they can work. But science has not proven it yet, and therefore, perhaps you are comfortable taking that risk. Okay, fair enough.
Science also has not pinpointed the moment of life. It is a philisophical question---and each individual's answer will be swayed by their world view. Since science cannot answer such a question, some people have decided that the risk is worth the procedure. You don't believe that fertilized eggs are being expelled after implantation---they don't believe they are ending a life they are not convinced has started.
As I have said before---your understanding of the bigger question is just as valid as someone else's. That's what choice is all about. Some people would not use iud's or hormonal birth control, because even the chance they could interupt the process is wrong to them. Others are not convinced the same----and neither are absolutely right or wrong----it has not been answered.
So I understand your question. There simply is not an answer. Not without bringing in individual philosophies----and those differ a great deal.
NC