STORY HIGHLIGHTS

China ‘parasitic twin’ case: A one-year-old child in Shanghai, with an enlarged head, was discovered with a rare condition in which her brain was hosting an “alive” unborn twin. 

An “unborn twin” was discovered in the brain of a one-year-old child in China’s Shanghai. The revelation added to the fewest of the few cases of a condition called ‘fetus-in-fetu’, in which the twins become conjoined in the mother’s womb but only one of the two continues to develop. 

How was it found?

According to the study published in Neurology journal, the condition was discovered after the child was brought in to medical attention after she showed problems with movement-related bodily functions and had an enlarged head.

After a primary examination, the doctors in Shanghai found that the foetus of the unborn twin had developed in the host child’s brain. The unborn twin was “alive” due to constant blood supply but was not developing any further.

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

Fetus-in-fetu: Why is it called parasitic twin?

The condition, fetus-in-fetu, is also referred to as parasitic twin. According to a report in IFL Science, fetus-in-fetu cases occur during the start of pregnancy. It occurs when a cluster of cells formed after fertilisation between male sperm and female egg, fails to separate properly. After this, one of the early embryos gets enveloped by the other.

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

The fetus-in-fetu or ‘parasitic twin’ cases are rare. However, they have been found earlier as well. In 1997, a foetus was discovered inside the abdomen of a 16-year-old teenage boy. In November 2022, eight embryos were removed from the stomach of a 21-day-old infant in Central India’s Jharkhand state.