Baby in India born 'pregnant' with his half-formed twin

Half-formed, seven centimeters in length and weighing only 150 grams, with a brain and limbs, the fetus had formed in his twin brother's abdomen in a case that has astonished India's medical fraternity.

After his birth on July 20 at Bilal Hospital in Thane, near Mumbai, pediatric surgeons at a separate hospital operated on July 25 to remove the unborn twin.

"Both the mother and baby are doing fine now. The mother will begin feeding him soon," gynecologist Neena Nichlani told the Times of India.

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The 19-year old mother was not aware she had a monozygotic twin pregnancy, where the twins shared the same placenta, with the one fetus drawing nutrition from the other.

In early July a mass with bones present was discovered in the fetus' abdomen during a routine scan of the pregnant mother. (partially formed fetus could not be detected antenatally as it appeared to be a cyst.

"In the postnatal scans, we spotted another half-formed baby with a brain, arm and legs in a fetal sac in the baby's abdomen," radiologist Bhavna Thorat told the German press agency dpa.

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"The mother had conceived twins, but here a twin got enveloped in the body of another twin, leading to a condition of a host baby and its parasitic twin, who grew up to 13 weeks and then stopped," she said.

Only 100-200 cases of this kind have been documented worldwide. A fetus-in-fetu is estimated to occur once in every 500,000 live births.