Sometime on Monday, a baby was born who helped push the human population on this planet to 7 billion, say estimates from the United Nations Population Fund.

Amid the millions of births and deaths around the world it is impossible to peg any individual baby as the globe's 7 billionth occupant, so instead the UN marked the day with festivities worldwide and a series of symbolic births.

Nations, including India, South Africa and Nigeria all claimed, and honoured, babies born on Monday as No. 7 billion in the world.

In India, a country where the population grows at a rate of nearly one person every second, seven baby girls were chosen to symbolize the population landmark.

India doesn't have the world's largest population growth rate, but its fertility rate still hasn't dropped as much as government officials would like.

And the country struggles with a deeply held preference for boys, which has resulted in millions of aborted female fetuses and a skewed sex ratio. According to U.S. government estimates, India has 893 girls for every 1,000 boys at birth, compared with 955 girls per 1,000 boys in the U.S.

"It would be a fitting moment if the 7 billionth baby is a girl born in rural India," said Dr. Madhu Gupta, an Uttar Pradesh gynecologist. "It would help in bringing the global focus back on girls, who are subject to inequality and bias."

The chosen Indian babies were being born at the government-run Community Health Center in the town of Mall, on the outskirts of Lucknow.

Six babies were born from midnight to 8 a.m. and four were boys.

India is also battling to keep track of the people it already has. Few Indians have passports and recordkeeping in rural areas is often poor; many in the country don't know their own birthdates.

But a new program, called the Unique Identification Authority of India (UIDAI) is helping, reports CTV's Janis Mackey Frayer from New Delhi.

The government program is fingerprinting and scanning the irises of 700,000 people a day to build a database of its population.

In a country that struggles with undocumented citizens and problems, fake identities, this is a significant development, says Nandan Nilekani, chairman of the UIADI.

"They go from being nameless, faceless, anonymous non-persons to a people with an ID in the system," he said. "It's a huge part of empowerment and self-esteem."

There are currently 1.2 billion people in India, and its population is expected to grow to 1.6 billion by 2030, when it's expected to overtake China as the world's most populous nation.

China currently has 1.34 billion citizens but its fertility rate is steady, thanks to its strict one-child policy, which for three decades has limited most urban families to one child and most rural families to two.

"Overpopulation remains one of the major challenges to social and economic development," Li Bin, director of the State Population and Family Planning Commission, told the official Xinhua News Agency.

In Lagos, Nigeria, twin boys were born to 32-year-old hairdresser Seun Dupe. Officials say that Lagos is expected to surpass Cairo as the continent's most populous city.

Large families remain the norm in rural areas of Nigeria, with many women saying they plan for around three or four children, said Dr. Femi Omololu of Lagos Island Maternity Hospital.

In South Africa, two baby boys were born at Charlotte Maxeke, a teaching hospital in Johannesburg.

One of the mothers, a 19-year-old unemployed woman, named her son Gwakwanele, meaning "enough."

A nurse at the sprawling hospital teased the new mother that she was too young to know whether this child would be her last. The mother smiled and said she was sure.

The rate at which the human population is growing is mind-boggling. It took until 1804 for the global population to hit one billion; it then took more than 100 years to hit 2 billion, which we did in 1927.

It was only 12 years ago we hit 6 billion, and at the rate we're going, the United Nations Population Fund estimates we'll hit 8 billion by 2025 and 10 billion by the turn of the century.

With files from CTV South Asia Bureau Chief Janis Mackey Frayer in New Delhi and The Associated Press