A woman or a man can dream of being pregnant. For a man, dreaming of being pregnant means he is anticipating the results of a project/ task/ event, which he had spent time and efforts.
If a woman dreams of being pregnant, it can carry the same meaning as for the man, that is, she is carrying a project and she expects results.
If a woman who is biologically fertile, has missed her menstruation, she may have thoughts and feelings about being pregnant. This also depends on her having active intercourse with her male partner. This stimulus becomes the trigger for the dream of being pregnant.
