Foetus in a dream: what does it mean?
A dream of something not yet born carries whatever the dreamer is actually living through, and the same image arrives to people hoping, people grieving and people deciding.
How do the four traditions read it?
Each reading below comes from a named tradition and a cited source, so you can see where it came from and decide what fits your dream. The four often disagree, and that is the point: a symbol rarely means one fixed thing, and the distance between Freud, Jung, modern research and myth tells you more than any single verdict could.
Freud
Freud would attend to what the dreamer expected the thing to become, since a dream of something incomplete has arranged a future that has not arrived. He would treat the state of not-yet as the material rather than the biology.
After Freud, The Interpretation of Dreams (Brill trans., 1913), public domain.Jung
For Jung an unformed figure can image potential that is real and not yet viable, and he treated such images as being about a process under way rather than about a person. Whether the dreamer felt protective or frightened is usually the reading.
Our summary of a Jungian reading, in our own words, not Jung's. See Jung, ed., Man and His Symbols (1964).Modern
Under the continuity view these follow real pregnancy, real loss, real fertility treatment and real decisions, and the plain reading is almost always the correct one. Anyone dreaming this during any of those is dreaming about the thing itself. Scan images are now so familiar that the dream frequently borrows one directly.
Our summary of the continuity hypothesis, named by Calvin Hall and Vernon Nordby, The Individual and His Dreams (1972). Its correct scope is disputed; see Domhoff (2017) and the replies to him.Mythological
Traditions attach elaborate protective custom to the period before birth, most of it about what a pregnant person may see, eat or do, and nearly all of it placing responsibility on her for outcomes she did not control. That is worth recording as history rather than as guidance.
Rosmerta Publishing editorial synthesis (after Frazer; Brewer).How can writers use this symbol?
The same symbol, read as craft material rather than as a dream. What it does on the page, how genres use it differently, and what happens when you turn it inside out. Written for novelists, screenwriters and poets who need the symbol to actually work, and it ends with something to try.
In literature
Writing about pregnancy from inside is a young literature and still thin, particularly on ambivalence, which is the most common feeling and the least represented.
Rosmerta Publishing editorial synthesis. Our own words; no quoted text.What it does in a story
It supplies a future with a date attached and no certainty, which is unusually strong as a source of tension. Structurally it changes what every other scene is about without ever needing to be mentioned.
Genre conventions
Literary fiction increasingly uses the scan room. Memoir uses loss and is where most of the honest writing is. Horror uses the unborn as threat, which is a very old and rather ugly tradition.
How to subvert it
Write a character who feels nothing at the scan and cannot say so to anyone in the room.
Try this
Write a twelve-week scan from the sonographer's side. Four hundred words. Professional throughout.
Only the first of these names a source. What a symbol does in a story, how genres treat it, how to invert it and what to try are our editorial judgement as writers and editors, not findings from a body of research. They are offered as craft opinion and should be argued with.