Celebrations have been held around the world to welcome symbolic "seven billionth" babies in recognition of the global population reaching the demographic milestone.
The United Nations said the seven billionth baby was born on Monday and instead of celebrating one birth, various countries recognised the landmark.
But critics have warned it should not be a moment of celebration due to growing fears about expanding populations and the strain they are placing on the planet.
The Philippines was the first country to declare a seven billionth baby when Danica May Camacho was born in Manila's Jose Fabella Memorial Hospital.
Her mother Camille Dalura, cradling the baby girl, said: "She looks so lovely. I can't believe she is the world's seven billionth."
UN officials presented the child with a cake and local benefactors also gave a scholarship grant and financial package to help her parents open a general store.
Other countries honouring babies included Bangladesh, Cambodia, India, Laos, Vietnam, Zambia, Russia, the Ivory Coast, Papua New Guinea and the Maldives.
Another baby girl named Oishee in Bangladesh arrived a minute after midnight at a hospital in the capital Dhaka and was named the seven billionth child.
Her father Mohsin Hossain said: "I'm so happy. I've become the father of a baby girl at a historic moment."
But Indian health minister Ghulam Nabi Azad said the milestone was "not a matter of joy but a great worry".
"We shouldn't be celebrating the birth of the seventh billionth child... For us a matter of joy will be when the population stabilises," he told The Times of India.
India's population is the world's second biggest at 1.2bn and is set to surpass China's by 2025, according to the US census bureau.
Twelve years ago, in October 12, 1999, the UN named a Bosnian child Adnan Mevic as the Earth's six billionth inhabitant.
The secretary general at the time, Kofi Annan, was pictured in a Sarajevo hospital with the boy in his arms but his family is now living in poverty.
This is partly why no single baby is being put in the global spotlight this time and a number of births are being marked throughout the day.
Back in 1922, before the start of the great demographic expansion, the world's population had not reached two billion but it has now doubled in 50 years.
There is mounting concern about the environmental impact and that there will not be enough food to feed everyone in just 100 years' time.
UN Secretary General Ban Ki-moon says the seven billionth baby is entering a "world of contradiction".
"Plenty of food, but still a billion people going to bed hungry every night. Many people enjoy luxurious lifestyles, but still many people are impoverished," he told Time magazine.
At a New York school last week, he added: "Seven billion people who need enough food. Enough energy. Good opportunities in life for jobs and education.
"Rights and freedoms. The freedom to speak. The freedom to raise their own children in peace and security. Everything you want for yourself - seven billion times over."
With about two babies born every second, the population is set to continue soaring ahead and the UN estimates it will top 10bn by 2100.