The Independent published this article:

Doctors in China have found an “unborn twin” in the brain of a one-year-old child in China, according to a new study.

The study published in Neurology journal in December revealed that the child was brought in after she presented problems with motor functions and had an enlarged head.

Doctors in Shanghai found that the fetus of the unborn twin had developed in the host child’s brain.

“An intraventricular fetus-in-fetu, a malformed monochorionic diamniotic twin, was identified in a 1-year-old girl with motor delay and enlarged head circumference,” the study said.

Fetus-in-fetu, sometimes called a parasitic twin, occurs when twins become conjoined in utero, but only one continues to develop, reported the Miami Herald.

The study added that the fetus was found to be the child’s twin after genome sequencing.

According to a report in IFL Science, fetus-in-fetu cases such as this occur during the very early stages of twin pregnancy when the cluster of dividing cells made by a fertilized egg, called the blastocyst, fail to separate properly.

As a result one of the early embryos become enveloped by the other.

Encased by the other twin’s replicating cells, it fails to develop but remains “alive” due to receiving blood supply.

“The conjoined parts develop into the forebrain of host fetus and envelop the other embryo during neural plate folding,” the study said.

While such cases are rare they have been found earlier as well.

In 1997 a foetus was discovered inside the abdomen of an Egyptian teenage boy where it had been lodged for 16 years.

Last November doctors in Ranchi in India’s Jharkhand state removed eight embryos from the stomach of a 21-day old baby girl. Doctors said the size of the fetuses ranged from 3cm to 5cm and were settled inside a cyst in the abdomen.