The world's 7 billionth person will be born into a population more aware than ever of the challenges of sustaining life on a crowded planet but no closer to a consensus about what to do about it.

No-one knows what circumstances the baby will be born into, but India's Uttar Pradesh - with a population that combines that of Britain, France and Germany, in a country expected to overtake China as the world's most populous by 2030 - provides a snapshot of the challenges it could face.

Pinky Pawar, 25, is due to give birth in Uttar Pradesh at the end of the month and is hoping her firstborn will not join the estimated 3 billion people living on less than $2 a day, with little hope of an education or a job.

"I want my child to be successful in life, so I must do my best to make this possible," she said, her hands over her swollen belly as she sat outside her mud and brick home in Sunhaida village.

United Nations Secretary-General Ban Ki-moon was optimistic about the world's 'strength'.

"Some say our planet is too crowded. I say we are seven billion strong," he said .

"In our increasingly interconnected world, we all have something to give and something to gain by working together. Let us unite, seven billion strong, in the name of the global common good."

The United Nations have even released an anthem to celebrate October 31 - the date experts believe will mark the birth of the 7 billionth child.

While growing populations could be a drain on the world's resources, the U.N.'s Population Fund's 'The State of World Population 2011' released on Wednesday said a contributing factor was overconsumption by the existing population.

"With planning and the right investments in people now, to empower them to make choices that are not only good for themselves ... our world of 7 billion can have thriving sustainable cities, productive labour forces that fuel economies, and youth populations that contribute to the well-being of their societies," Osotimehin said in the report.

It was vital to engage with the world's youth and to harness their entrepreneurial skills to boost economies and prevent potential alienation, the report said.

Those under the age of 25 make up 43 per cent of the population, and as much as 60 per cent in some countries, and this group must be educated and trained if countries are to have a dynamic work force, it said. Failure to do so would see a loss of ideas, innovation as well as tax income.

A major contributor to the recent Arab uprisings was a youth unemployment rate of nearly 25 per cent, the report quoted the International Labour Organisation as saying.

Fertility and migration

The U.N. also said migration will become more significant in the coming century, with people moving across borders as well as within their own countries.

The report looked at nine countries to see how they were responding to different rates of fertility and migration.

In some of the poorest countries, high fertility rates have stunted development and perpetuated poverty, the report said.

Getting girls to school and providing women with jobs and equal opportunities as well as sexual and reproductive healthcare including family planning was essential, it said.

In some of the richest countries, low fertility rates and too few people entering the job market have raised fears about the prospects for sustained economic growth and the viability of social security systems.

Every country has a population that is ageing to some degree. The global proportion of people over the age of 60 is expected to grow from 11 per cent in 2009 to 22 percent in 2050.

In Finland, which enjoys a high standard of living but where low fertility rates have led to a quarter of the population being over 60 years old, the emphasis is on excellent social services to make parenthood easier.

Academics have said that in countries such as China, which is getting older before it gets richer, there is need for old-age security, medical care and social services.

More funding, including from governments and foundations, was needed, Osotimehin told reporters at the media conference.

"Family planning, for instance, has not been funded as much as it should have been," he said.

A U.N. Secretary General report showed that $68 billion would be needed in 2011 if its programme on sexual and reproductive health initiatives set out in Cairo in 1994 was to be met, Wednesday's report said.

Countries were expected to contribute $34 billion, with a further $10.8 billion coming from international and bilateral donors, leaving a shortfall of around $25 billion.

Growing global interdependence meant governments had to work out how to deal with record populations if they were to avoid future competition for limited resources such as food and water.

Reports already suggest a 40 per cent global shortfall in water supply by 2030, while developing countries are buying up land in Africa to offset any future shortages at home.