Earlier this year, a farmer in the southern Indian state of Andhra Pradesh made a shocking discovery.

Sticking out of the earth was a tiny human hand - and barely audible, the cries of a newborn baby. The farmer had found a two-day old baby girl who had been buried alive.

The baby was still conscious and was rushed to a local hospital to recover from her ordeal. Her grandfather meanwhile confessed to the girl's attempted murder. With seven daughters already, he claimed he could not afford the burden and expense of looking after yet another girl.

This girl survived. But every year in India, tens of thousands of baby girls are killed - simply because of their gender. Most are aborted as soon as their sex is determined. Some are abandoned at birth, while others are killed, shortly after. This slaughter is all part of India's centuries-old preference for boys, who will carry the family's name and traditionally provide for parents in their old age.

At an orphanage in the nearby town of Kadapa, its the first birthday party for Harsheeta - a baby girl who was abandoned at the gates of the orphanage when she was only two months old. There are eighty children here, nearly all of them are girls. Most have no idea of when their real birthdays are - since they arrived as babies or small children.

Sandhya Reddy who runs the orphanage explains that girls are seen as a financial burden, who will join another family after the payment of an expensive dowry. Upstairs at the orphanage are village women learning skills for the first time. One is about to wed. She weeps as she recalls how her mother has had to sell her prized gold to pay for her wedding and her sisters have been forced to abandon their education.

So great is the burden that girls are seen to place on a family, that some believe it is better that they are never born. In the past, infanticide was seen as one solution. Now with advances in medical technology, many parents are resorting to ultra sound scans to determine the gender of the baby. In India, it's illegal to test the sex of a foetus - but the practice is widespread. If it's a girl, they pay for an abortion.

For the past fifteen years, sex selection tests and abortion on the basis of gender has been banned in India. But the law has simply forced the trade underground. In the neighbouring state of Orissa, dozens of aborted female foetuses were recently uncovered in a well belonging to a clinic carrying out illegal sex selection tests and abortions.

Sex selection in India is not just restricted to the poor. It's also routine among the country's moneyed middle classes - though rarely spoken about. In the prosperous city of Ahmedabad, capital of Gujarat state, Pooja Salot is one woman who has dared to speak out. She is married to a multi-millionaire industrialist.

She claims he forced her to abort two pregnancies simply because they were girls - adding that such abortions are commonplace among her wealthy friends. Now she's decided to reclaim her self-respect and has gone to the police.

Her husband and her in-laws have been arrested, charged with harassment and obtaining illegal sex determination tests and abortions.

Back in Kadapa, Sandhya meets another one of her trainees who is pregnant. Rawadevi is due in only five weeks and knows she is carrying a girl. She tells Sandhya she would have aborted her girl child already if she had had the money.

Rwadevi pleads with Sandhya to take her babygirl to her orphanage after she gives birth. But Sandhya wants to convince her of the importance of a mother's bond with her newborn. Despite her efforts, Rawadevi is unsure what to do.

A month later, Rawadevi gives birth. And Sandhya manages to convince her to keep the girl - at least for the first year of its life. It's meant survival and hope for one more baby girl.

India's Missing Girls will be on on BBC2 on Monday 22nd October at 7pm.

Producer / director: Ashok Prasad