Life and Death.  I believe that the author has a deep message of life and death and having gratitude and emotions that he/she portrays through symbolism such as objects like an elevator, casket, umbrella, etc...  Each item representing an experience and realm of emotions.  Elevators go unappreciated, however here we can clearly see that it can be used to help properly deliver life to this world, easily lifting a woman in labor.  A body compared to a casket represents the frustration and passion in her desire to rid her body of her dead child.

The story is now cleverly being told from the dead fetuses perspective as if to say it has a voice too.  We often forget about how a dead child feels in its loss of life before it even began.  Here we can see a dead baby's spirit looking for empathy and compassion unhappy that its mother has such disgust with its mere presence. The fetus has no issues moving on into the next life.  The mother is hurting but her own pride is what is causing the excess pain.  Gratitude is too much of a stranger.

The mother is now in a heap of negative thoughts and depression dwelling on the fact that she doesn't have what she wants.  She wants to be so proud of her potential kid overlooking the meaning of what happened and growing from her loss as result, misunderstanding how precious life is and to live it to the fullest rather than being so bitter.  She even goes as far to mock the child's death by wishing it an unborn birthday.  The mother is too caught in her own sorrow.  She represents the life condition of hell of the average human being of the latter day of planet Earth.