According to the Hong Kong Medical Journal, a baby girl was born "pregnant" with what proved to be twin fetuses in her abdomen.
This girl was born in Queen Elizabeth Hospital in November 2010. The fetuses in her abdomen had four limbs, a spine, rib cage, intestines and an anus, and they were believed to eight to ten weeks of gestation.
It is believed that the "babies" were fertilized eggs that got absorbed into her body as she developed. It is believed that the twin fetuses were developing at a slower pace than the girl and that could be the reason of absorption.
The scientific term of this abnormality is called "fetus in fetu", which signifies the existence of a fetus existing inside another fetus.
It is an extremely rare condition, which occurs in one in every 500,000 births in the world. And there are approximately less than 200 such cases that have been reported.
According to the clinical reports written by the Hong Kong Medical Journal, this was a singleton pregnancy from a natural conception. And as the mother was a resident of China, she received her obstetric care and there were no ultrasounds done in her second trimester.
This abnormality wasn't detected until the detailed antenatal ultrasound was done at 37 weeks of maturity which showed the twin fetuses of 32 mm x 30 mm x 30 mm mass in the abdomen of the baby girl.
Besides that, there were no apparent abnormalities, or complications in the baby's intestines.
It was decided that the twin fetuses inside the baby girl would be surgically removed.
According to the World Health Organization, there is no specific reason behind this abnormality, but it is considered as a variant of mature teratoma, which is a type of cancer.
