The baby named Saybie was born at 23 weeks and three days and was sent home this month weighing 5 pounds (2 kilograms) after almost five months in the neonatal intensive care unit, Sharp Mary Birch Hospital for Women & Newborns said in a statement.
Her mother gave birth to her through an emergency C-section, three months ahead of schedule, after bring diagnosed with preeclampsia - a pregnancy complication characterised by high blood pressure and damage to another organ system.
Instead of a normal 40-week gestation, hers was only 23 weeks and 3 days. "I just felt very uncomfortable, and I thought, maybe this was part of the pregnancy".
The father was told by doctors that he would have about an hour with his daughter before she passed away. "Doctors said the preterm birth was necessary after they found that the baby was not gaining weight and her mother's life was at immediate risk".
Saybie spent about five months in the NICU before she was released earlier this month.
She is believed to have broken the record for the world's tiniest baby, according to the Tiniest Babies Registry.
After nearly five months in a neonatal intensive care unit, the baby girl, who was nicknamed Saybie by the staff, left the San Diego hospital earlier this month and instantly earned a place in the history books.
But despite the low odds, the nurses and Saybie's parents kept fighting for her.
Despite her small size and the host of health complications that can potentially be deadly for a "micro-preemie", or a premature infant born before 28 weeks, Saybie lived.
Babies born before 24 weeks, micro-preemies, experience more medical problems than babies born later, including brain bleeding and poor heart function.
Baby Saybie, who was born in December and weighed the same as an apple at only 8.6 ounces, has been described as a "miracle".
Saybie's family have given permission to share her story, but chose to remain anonymous.
"She was a fighter from the get-go", said Kim Norby, a nurse.
A pink sign by her crib read "Tiny but Mighty".
But against all odds, Saybie did survive.