The first baby to be picked as the world's seven-billionth was Danica May Camacho, born at two minutes to midnight in Manila, the Philippines, reports the Associated Press.
Born a month premature and weighing 5.5lb, baby Danica was welcomed by parents Camille Dalura and Florante Camacho, local and U.N. officials, and a throng of photographers.
More from GlobalPost: World population reaches 7 billion
Well-wishers presented her with gift certificates, a scholarship fund, and a special cake saying "7B Philippines".
Admitting her concern at the Philippines' soaring population rate, Danica's mother Camille said she had decided to begin using birth control, despite her Roman Catholic faith:
"The number of homeless children I see on the streets keeps multiplying. When I see them, I'm bothered because I eat and maybe they don't."
Meanwhile in India, another newborn girl was hailed as a seven-billonth baby, the BBC reports.
Her name is Nargis, meaning "beautiful flower", and she was born at 7:25 AM in the village of Mall in Uttar Pradesh, India's most populuous state.
More from GlobalPost: Baby Nargis from India is number 7 billion
Children's organisation Plan International picked Nargis for the title to highlight the problems of female foeticide. More than half a million female foetuses are aborted in India every year, the group says.
It would be impossible to identify the world's actual seven-billionth inhabitant with any certainty, points out the BBC.
The U.N. chose Monday, October 31st as "7 Billion day" according to its estimates, which it recognizes could be up to 56 million out.
According to the U.S. Census Bureau, the global population will not hit the seven billion mark until March or April 2012.
Other children picked out by the U.N. to mark previous population milestones have complained that the organisation "forgot about them" later on, says the Guardian.
The world's six-billionth baby, 12-year-old Adnan Nevic of Bosnia Herzogovina, told the paper that once the celebrations were over he had been ignored:
"[Former U.N. chief Kofi Annan] held me up when I was two days old, but since then we have heard nothing from them."
You can estimate where you came in the world's seven billion using the BBC's population calculator.