By Ng Wan Ching

CAN a 1-year-old girl be pregnant?

This was the gossip revolving around an abandoned girl in China last year, with neighbours even calling her a "monster".

A series of tests by doctors showed that Kang Mengru was "pregnant" with her twin brother.

The girl was abandoned by her mother when she was only 3 days old.

She was taken in by a childless couple in Luohe City in the central Chinese province of Zhenzhou soon after. Within months, her stomach began to swell.

She was found to suffer from a condition called foetus-in-fetu - where a twin becomes trapped inside the developing body of its sibling.

In Mengru's case, doctors said she could die if the growth was not removed.

Chief surgeon Dr Zhang Xuedong told The Sun that it took a 10-hour operation last year to remove the foetus and another month for Mengru to fully recover before she could go home.

"There was a very real risk of cardiac arrest," he said, adding that pressure on her chest and belly was high.

Doctors here say there are two theories on how the condition occurs.

One theory states that a mass of tissue begins as a normal foetus but becomes enveloped inside the body of its twin.

Said Dr Christopher Ng, obstetrician and gynaecologist at Camden Medical Centre: "Very early in a monozygotic (identical) twin pregnancy (where both twins share the same placenta), one foetus wraps around and envelops the other."

Identical twins develop when a single egg is fertilised to form a cell, which then divides into two separate embryos.

The enveloped or parasitic twin depends on the host twin for its blood supply.

"Most of the time, the parasitic or enveloped twin dies before birth as it relies on the host twin for oxygen and nutrients, as they share a single umbilical cord," said Dr Ng.

Sometimes, the enveloped twin can continue to grow past birth by developing a new umbilical cord directly into its twin's blood supply.

Foetus-in-fetu is rare, estimated to occur in one out of every 500,000 live births.

But in Mengru's case, Dr Ng does not think it is a case of a parasitic twin. Reports say her twin brother was inside her, but monozygotic twins are always of the same sex, said Dr Ng.

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