“A 16-month-old Alabama boy who weighed less than a pound when he was born at 21 weeks and one day has set a world record — being named the most premature infant to survive, according to Guinness World Records.”

https://nypost.com/2021/11/11/infant-breaks-world-record-as-most-premature-baby-to-survive/

New world record is 21 weeks and 1 day.

https://nypost.com/2021/11/11/infant-breaks-world-record-as-most-premature-baby-to-survive/