Population: India: Devotion to the son will take numbers to a billion

A tiny, listless baby lies on a string cot in a Delhi slum. His name is Kishen, and he is two months old. He is the eighth child of Lachmi and Chander but he will be their last. Lachmi, his mother, is going to be sterilised.

Kishen's seven siblings are all girls. Year after year Lachmi has come to term in the single room that is the family's home, with the help of the local midwife. Year after year the couple has struggled to raise the family on the pittance Chander earns as an occasional day labourer. And year after year he has put up with the men in the neighbourhood taunting him, as each new daughter emerged, that he was not virile enough to sire a boy. Finally, Kishen emerged to prove them wrong, and his parents could call it a day. "They said I would never have a son," Lachmi says now, wreathed in smiles. "But God has finally granted our wish."

Little Kishen's story epitomises the nightmare of India's population explosion. At the first census after independence, in 1951, India had a population of 361 million. Today it is not far off one billion, and still growing fast. By 2050 it should overtake China's. While states such as Kerala and Tamil Nadu, with their high literacy rates, have had extraordinary success in bringing fertility down - dwarfing the results achieved by coercion in China - in the desperately poor "Hindi belt" of northern states, where women are still bullied into being sterilised and penalised if they refuse, the population continues to boom. The social pressure to have sons - whether to earn as child labourers, or to light the father's funeral pyre, or from a mixture of motives - remains intense. But even here there are glimmers of hope. Lachmi was married off before puberty, but she will not inflict that custom on her own daughters. Such changing attitudes are reflected in the statistics. Fertility in India has dropped more than 40 per cent in the past 25 years, a far steeper decline than World Bank and United Nation experts predicted. If present rates are maintained, stability - what is called "replacement fertility" - will be reached as early as 2016.

That is the good news. The bad is that as a very large proportion of the Indian billion is young, and momentum will carry the population steeply upwards in the next few decades.

- Peter Popham, New Delhi