That's a skewed way of looking at things, dear friend. Then we can say that children "take over" our lives. That may be true in some case, but if we allow them. The same can be said of pets.
What happens in human mothers happens in all mammalian mothers. This is not some specially designated gift from God to humans. If a mother wants to smoke and drink, or use drugs during pregnancies, and not take care of herself, the "product" can do nothing to force her to do otherwise. And, the mother's behavior can lead directly to the premature expulsion of the "product." The "product" has no control over nay of it.
It's growing in the body the way tumors grow, sapping the nutrients and oxygen from the host. It is "parasitic" in that sense; and when the parameters established by natural law have been reached, the product is expelled, not by its will but by the will of the body that carries it, the autonomic nervous system over which neither the mother nor the offspring have any control.