Juan Pedrito is, indeed, the baby son of main character Cleofilas Enriqueta De Leon Fernandez and her husband Juan Pedro Martinez Sanchez in Sandra Cisneros's short story about domestic abuse and the search of the self "Woman Hollering Creek".
Cleofilas is a young, naive Mexican woman whose entire life has been based on her hopes that it would turn out the way it does in those Mexican "novelas" (soap operas) that feed her psyche. When her father gives her hand in marriage to Texan Juan Pedro, Cleofilas is positive that her novela has just begun. She really believes that Juan Pedro is her "knight in shining armour", and she happily agrees to marry him.
Unfortunately for Cleofilas, not only is Juan Pedro a fat, ugly and broke alcoholic, but he also abuses her both mentally and physically. Hence, after summoning her strength she is finally able to escape the marriage with baby Juan Pedrito and thanks to the help of two very independent women in the characters of Felice and Graciela.