The image was was posted on Reddit on 1 January with the heading "A friend’s ultrasound. When you see it…"
It has sparked an online debate about whether the shadowy shape to the right of the baby is a "demon" or a "goddess".
Redditor luigivampa-over9000, who uploaded the image, claimed to be friends with the parents, who he said were "freaked out too".
"Everything is fine now," wrote luigivampa-over9000 in an update. "The baby was premature by two months.
"They asked the tech who did the ultrasound what it was - they didn't really have an answer besides they haven't seen something like that before."
The post quickly racked up more than 200 comments with debate raging over whether the mysterious figure was good or evil:
The post also prompted some parents to share their - equally freaky - ultrasound scan pics: