The thing wrong with most of your parasitic comments is that not all parasitic relationships are bad.
There are five forms a parasite can enter a relationship into are called symbiosis.
Mutualism - Both species benefit
Commensalism - one species benefits, the other is unaffected
Parasitism - one species benefits, the other is harmed
Competition - neither species benefits
Neutralism - both species are unaffected
Every mammalian animal at some point fed off of its mother. Technically, the creature was a parasite (throw it into any category besides the last two) who ate what the mother ate and inhaled what the mother inhaled. The blood that ran through it was not it’s own, but that of its mother.
The person who said the original post probably classified the unborn babe in a parasitic relationship with the mother, which is acceptable because the babe was taking nutrients from the mother whilst the mother went through physical and psychological changes. If the egg, for example, grew in the fallopian tube (called ectopic pregnancy), and the mother would die if the babe continued to thrive and get larger, then this would be physical harm to the host and would classify as parasitic (for the unborn babe was still benefiting from nutrients while the mother was going to die as it kept taking).
…that’s all I got…