I know what happens when people assume (LOL) but I am assuming that once he is grown, there is no use for the woman, so she becomes sick? Or did I miss something about her illness/death?
I must say that from the start, I knew that "released" meant death.
The goal of the movie was to make you think about its supposed deeper meaning for which there isn't one.
My only takeaway was that the filmmakers wanted to portray humanity as being just as cyclically irrelevant as the dead baby birds we find in the garden on a Sunday afternoon and it used the scheming life cycle of the Cuckoo chick as a parallel to human procreation. The shortcoming to me was that they used science fiction/horror as a framework when they could have just used a real world example which would have made the human characters more relatable. Instead, this just felt like an extended episode of Black Mirror. Even Rod Serling would have worked in an ironic twist to this story instead of a straightforward progression with no character or story arcs.