Dependent is dependent. Period.
No it doesn't, the mothers body WILLINGLY shares nutrients with the baby whereas a parasite basically sucks it out forcefully (baby's have umbilical cords parasites act like vampires)
Yes, ticks have different DNA, BUT while a baby's DNA is different, its still human. Perfectly identical = part of the person, completely different = not human, a fetus = close enough to be identifiable as human but it's own individual.
Also definition of a fetus:
fe·tus
/?f?d?s/Submit
noun
an unborn offspring of a mammal, in particular an unborn human baby more than eight weeks after conception.
synonyms: embryo, fertilized egg, unborn baby, unborn child
"antibodies are passed via the placenta to the fetus"