What does it mean when you dream your sister is pregnant and she pretend to be dying?

Dreams are about the dreamer's own feelings and thoughts. In this dream, the sister-in-law could represent the dreamer, and her own suppressed desires and fears about becoming pregnant. Alternatively, the "pregnancy" and "baby" might symbolize some idea, project or task the dreamer or the dreamer's family has undertaken, and the dreamer's fears that the project will fail.