Originally Posted by
Dhrizzle
Biology involves more complexity than you get from single sentences. In all but a few cases, none of which are human, in a parasitic relationship the "host" refers to a different species, and in those cases where an organism does use members of the same species as a host it reproduces behavior it uses on other species.
As both mother and child have to work together to make the biological relationship work, and carrying a child increases the (evolutionary) fitness of the mother, a more accurate description would be symbiotic.