As the world's population reaches six billion, countries such as Bangladesh face increasing pressure from overcrowding.

Bangladesh has had relative success with birth control programmes, but nowhere is population pressure felt more keenly.

Three times more densely populated than India, with an estimated 126 million people, it is the world's ninth most populous country.

Yet family planning and birth control campaigns are considered to have been more successful in Bangladesh than in many other countries.

Half of all Bangladeshis live in poverty

The birth rate has halved in the past 25 years, bringing the annual population growth rate down to 1.7%.

Experts say it would be difficult, if not impossible, to reduce population growth further.

But four babies are born every minute in Bangladesh and the United Nations says the population may almost double by the middle of the next century.

"Bangladesh has made some remarkable achievements in population programmes," says Shuyun Xu, the UN Population Fund's representative.

"The knowledge of family planning is almost universal. But then, because of the large number of young population, the population growth will continue.

"Those implications of course have a very unfavourable impact on the country's social and economic development."

One-fifth of Bangladeshis are below the age of 20 and half the country's people live in poverty.

The number of poor people will inevitably increase as the population continues to grow.