A pregnant baby sounds crazy, right?! Although bizarre (and extremely rare) it is a possibilty, even having a total of 200 diagnosed cases in the world. The Hong Kong Medical Journal recently reported a case from November 2010, in which a baby girl was diagnosed with a retroperitoneal tumor in her abdomen. However, after an ultrasound and further testing, it was found that each mass contained a spine, rib cage, intestines, four limbs, and even an umbilical cord — confirming the baby girl was actually pregnant with twins.

This condition, known as “fetus-in-fetu” is an uncommon circumstance that happens as a result of multiple fertilizations from the child’s parents. These additional fertilized fetuses mistakenly embedded into the baby girl and then grew to about 8- or 10-weeks-old. Thankfully, the fetuses were successfully removed from the girl at just two weeks old.

Fetus-in-fetu is thought to occur in an estimated 1 in 500,000 births worldwide. However, it is difficult to detect due to the embryo inside the baby being so small.

In other news, if the above case isn’t strange enough, this Pregnant Baby Doll is a horrifying, exaggerated example of fetus-in-fetu and will consequently give me nightmares for weeks. Excuse me while I go double triple check my birth control.