The Interpretation of Dreams by Sigmund Freud Chapter 6 Page 40

I therefore content myself with the mere assertion, and will cite an example, not for conviction but for explication.

The hysterical vomiting of a female patient proved, on the one hand, to be the realization of an unconscious fancy from the time of puberty, that she might be continuously pregnant and have a multitude of children, and this was subsequently united with the wish that she might have them from as many men as possible. Against this immoderate wish there arose a powerful defensive impulse. But as the vomiting might spoil the patient's figure and beauty, so that she would not find favor in the eyes of mankind, the symptom was therefore in keeping with her punitive trend of thought, and, being thus admissible from both sides, it was allowed to become a reality. This is the same manner of consenting to a