The Undertaking — N.R. Wick

Joanna was a star gymnast at Pencourt High, had a great social life, and perfect grades until a mysterious pregnancy prompted her parents to remove her from school and away from her friends. Now she's close to giving birth and strange things are happening to her. Disturbing thoughts plague Joanna's mind while she fights the burning desire to harm people. Worst of all, a sinister man is stalking her. Does he know what happened to her the night of a party that resulted in her pregnancy? Or will Joanna kill someone before her baby's born?

The Undertaking is a young adult short story from Dark Ascension: A Demon Anthology.