I just read such an intersting article.  It’s called When Does Pregnancy Begin?: A Federal Appeals Court Decision Implicates a New Abortion Question. It cites a federal lawsuit brought by the parents of a 16-year-old girl against the city of Philadelphia and a health center operated by the city’s Department of Health. They claimed that the health center gave the girl a “morning after” pill, at her request, but without informing her that the medication could prevent a fertilized egg from implanting inside her uterus. Her parents  say this information would have been significant because the “prevention of implantation constitutes an abortion according to their religious beliefs.”

The article then goes on to discuss when exactly pregnancy begins according to a medical view, vs. a religious view. From a medical point of view “pregnancy does not occur at the moment of conception. It occurs, instead, when an embryo (a fertilized egg that has divided over the course of a few days) attaches itself to the woman’s uterus, a stage known as implantation.” It goes on to discuss how the morning-after pill functions and how to define the term “abortion” in relation to this early stage.  Also interesting are the parallels drawn between this situation and in-vitro fertilization.

Anyway, I won’t try to summerize it any further but read the article here at FindLaw if you are interested in more details.