Doctors in Bangladesh say they have removed a long-dead foetus from the abdomen of a teenage boy who was complaining of stomach pains.
They said the foetus would have become the boy's twin had it grown normally in their mother's womb.
They said it was a case of an extremely rare condition where two foetuses are conceived as conjoined twins but one absorbs the other.
In 2003 Kazakhstan doctors removed a foetus from a seven-year-old boy.
Sixteen-year-old Abu Raihan was admitted to the Bangabandhu Medical University hospital in the capital, Dhaka on Saturday.
"After the operation we found a dead foetus weighing two kilograms (4.5lbs) in his abdomen," Doctor MA Mazid said, the AFP news agency reports.
"Apart from the head, all other limbs of the baby were developed."
The condition is known as "foetus in foeto", or inclusion twin.
"In this case the foetus of the baby entered into the foetus of the boy and continued to grow like a tumour in the boy's abdomen," gynaecology specialists Nurun Nahar said.
Hundreds of curious locals flocked to the hospital on hearing a rumour that a boy had given birth to a baby.
In April, 2003, doctors at Chimkent Children's Hospital in Kazakhstan discovered the dead foetus of a twin brother when operating on a seven-year-old boy.
The foetus had developed into a tumour but was found to have hair, nails and bones.