WITH the advent of invitro fertilisation (IVF), twin pregnancies have become common the world over. But in a remote village in Kerala, where the residents don't resort to medical treament to have babies, twins abound.

In Kodinhi, a tiny village of about 2,000 families in the Malappuram district of north Kerala, more than 300 have twins. The village records about 45 pairs of twins per 1,000 births, nearly six times India's national average.

Last year alone 15 pairs of twins were born in Kodinhi out of 300 healthy deliveries. This year the number is expected to grow.

Local doctor and twin enthusiast Dr Krishnan Sribiju has been studying the medical marvel of Kodinhi for the past two years. He is a dermatologist who works in a nearby hospital and is currently studying for his master's degree in public health. In his free time, he is trying to unravel the medical mystery.

He has a few theories. He told ABC News recently: "I feel that something in the environment is causing this unusual phenomenon. Maybe something in the water. Maybe something in the food."

He believes that most of the twins are fraternal although he has conducted no tests to confirm this.

Fraternal twins, which occur when two fertilised eggs are implanted into the uterine wall concurrently, can be either same or mixed sex.

Identical twins occur when one egg is fertilised, then splits into two separate embryos; they can only be of the same sex.

Although 250 sets of twins have been officially registered in the village, Dr Sribiju believes the real number is far higher.

"There are around 300 to 350 twins within the village boundaries of Kodinhi," he told The Daily Telegraph. "What is fascinating is the increasing numbers of twins with each passing year, so much so that I feel in the past 10 years the number of twins in Kodinhi has doubled."

News of the large number of twins was first broken by Kerala newspaper Malayala Manorama in 2001. Since then, Indian and foreign media have been flocking to the village.

According to Manorama, the village set up an association for the parents of the twins called Twins and Kin Association (Taka) in November last year.

"Taka has been set up to register and provide support for the twins of Kodinhi and their families," Mr Puallani Bhaskaran, 50, the association's president and the proud father of twin boys, told the Daily Mail.

"Twins are financially a strain and also they are medically complicated for mothers to bear. Taka can educate and support the villagers because here we have so many more twins than elsewhere," he added.

The residents of the area are not stopping with this. Malayala Manorama has it that they are all set to name two parallel roads in the village Twins Road.