What is the name of the first child born in the new millenium?

Depends when you say the new millenium began. The first baby born in 2000 is said to be a baby boy born at one minute past midnight in Auckland, but the parents have declined to release any details. The first baby girl born in 2000 is thought to be Tupou Fetuani, born 9 minutes later, also in Auckland.

http://news.bbc.co.uk/1/hi/world/asia-pacific/585133.stm

However, if you are being picky and saying that the new millenium began in 2001, I can't help you...

I'm saying that the millenium began in 2000, and I'm asking for the first child born in the year 2000. And Tupou Fetuani is NOT the right answer. Sorry, Liz.
It was Kala Sosefina Mileniume Kauvaka.

The first baby born in the year 2000:
Although the new century did not technically begin until 2001, she was considered, at the time of her birth, to be the first child born in the new millennium. She was born six minutes after midnight in Tonga. As the first baby of the millennium, she appeared in the Guinness Book of World Records alongside Robert Wadlow (the world's tallest man). Her parents were named Senituli and Ngaloa'afe.

https://www.famousbirthdays.com/people/kala-sosefina-mileniume-kauvaka.html

Because time zones roll over progressively around the world, there is no single, universally agreed-upon individual recognized as the absolute first child born in the new millennium. The title depends entirely on geography and how the millennium is calculated. Because the South Pacific nation of Tonga sits just west of the International Date Line, it was one of the very first countries to enter the year 2000. A baby girl born there just moments after midnight was officially celebrated as the first baby of the year 2000 and was fittingly named Millennium. Technically, the 3rd millennium and the 21st century did not officially begin until January 1, 2001 (since the Gregorian calendar started with the year 1, not the year 0). A baby girl named Khadija, born at exactly midnight on January 1, 2001, at the Millennium Hospital in London, was widely recognized in the UK and international news as the first official baby of the literal new millennium.