When does life matter?

A recent discussion about hot topic issues such as abortion and stem cell research has brought me to this question:
Is there a certain moment in time when life matters?

Does a life have to be "viable" to matter? I think not. I say this as a Mother who never had a chance to hold a child. As a Mother who only knew "the baby" in the abstract. A Mother who lost that life. Yet, there are those who claim that a developing fetus is nothing more than a "bunch of cells". Perhaps that is what they have to believe to feel comfortable in taking that life when it suits their needs. Of course a Mother of a sick child will support that which will help her child. I suppose it is easier to view the life that is supplying her child with stem cells as a non-entity. Does that need give a person in that situation to belittle my experience? To belittle my love for my unborn? To belittle the existence of unborn children, lost before they took their first breath? There are few things that bring back pain and hurt long buried than someone trying to take away the only "life" I created.