The baby, whom nurses at a San Diego hospital called “Saybie,” is believed to be the world’s tiniest surviving newborn. Sharp HealthCare hide caption

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Sharp HealthCare

The baby, whom nurses at a San Diego hospital called “Saybie,” is believed to be the world’s tiniest surviving newborn.

Sharp HealthCare

Her first life accomplishment was setting a world record.

A girl believed to be the smallest-ever surviving baby — weighing just over half a pound, or 8.6 ounces, at birth — has been released from a California hospital, officials revealed on Wednesday.

After almost 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.

Her parents decided not to allow her real name to be released.

Saybie was born prematurely at 23 weeks of gestation weighing about as much as a large apple.

Dr. Edward Bell of the University of Iowa, which maintains the Tiniest Babies Registry, confirmed that Saybie is the smallest baby the registry has ever recorded.

“Baby Saybie has the lowest birth weight among the infants in the Tiniest Babies Registry,” Bell told NPR. “The registry contains only those infants submitted and medically confirmed. We cannot rule out even smaller infants who have not been reported to the registry.”

Her mother was experiencing complications and underwent an emergency cesarean section after doctors discovered the baby was not gaining weight and the mother’s life was thought to be at risk.

Saybie spent almost five months in a neonatal intensive care unit after being born at about 23 weeks’ gestation. Sharp HealthCare hide caption

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Saybie spent almost five months in a neonatal intensive care unit after being born at about 23 weeks’ gestation.

Sharp HealthCare

Saybie was “a micro preemie,” a baby born before 28 weeks of gestation. The hospital’s statement notes that such babies often deal with serious medical challenges involving brain and lung problems, and they are more prone to infections, having spent less time with their mother’s blood supply. As a result, they rarely survive. (Babies are typically born after 40 weeks of pregnancy.)

“It was the scariest day of my life,” said Saybie’s mother in a video released by Sharp Mary Birch Hospital for Women & Newborns in San Diego. “I just felt very uncomfortable, and I thought, ‘Maybe this was part of the pregnancy.’ ”

At first, doctors were not confident Saybie would defy the odds, telling the baby’s parents to start preparing for the worst: Saybie’s father was told he would have about an hour with her before she would die.

“But, that hour turned into two hours, which turned into a day, which turned into a week,” said Saybie’s mother, whom the hospital has not named because she requested that she stay anonymous. It was distressing in the moment, the mother said, but she is now overjoyed looking back at what she now calls a “beautiful” experience.

A pink sign by her crib read “Tiny but Mighty.” When she left the unit, nurses placed a miniature graduation cap on her.

Now 5 pounds, Saybie was given a tiny graduation cap before she left the neonatal intensive care unit at the Sharp Mary Birch Hospital for Women & Newborns in San Diego. Sharp HealthCare hide caption

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Now 5 pounds, Saybie was given a tiny graduation cap before she left the neonatal intensive care unit at the Sharp Mary Birch Hospital for Women & Newborns in San Diego.

Sharp HealthCare

“She is the smallest baby,” the mother said. “But she’s mine.”

Saybie was about 7 grams lighter than the previous smallest baby, who was born in 2015 after 25 weeks of gestation in Germany, according to the registry.

Hospital officials say Saybie was discharged as a healthy 5-pound infant.

How did baby Saybie overcome the odds?

A mix of the right genetics and good luck, hospital staff have said, but some also believe a more inexplicable factor was at play.

“She’s a miracle,” said Kim Norby, a nurse in the hospital’s neonatal intensive care unit. “That’s for sure.”