I thought implantation-prevention was the whole point of the "morning-after" pill. If it doesn't have that effect, why administer it (not that I'm trying to make a case for it)?
I’m not expert, but the way I’m reading it is the difference between preventing fertilization and preventing implantation of the fertilized egg.
And, as a general rule, it’s best not to put much stock in mainstream media reports on the Church or Christianity in general until we get more facts or a transcript.
I believe that in some cases, morning-after pills can delay ovulation, which would reduce the change of conception from that act of intercourse. I wonder how they would find out the extent to which the pills prevent implantation of a fertilized egg, vs. how many times ovulation is affected. It seems like this would be all but impossible to test experimentally.