Baby Saybie was born at Sharp Mary Birch Hospital for Women & Newborns in San Diego, California, in December 2018. Weighing just 245 grams (8.6 ounces) and measuring a delicate 22.9 centimeters (9 inches), medics gave her just hours to live.

But five months later, she had grown into a healthy baby girl, weighing 2.5 kilograms (5.6 pounds) and able to leave the hospital for the first time. This makes her the smallest surviving baby in the world, as recorded in the official Tiniest Baby Registry maintained by the University of Iowa, officials at Sharp Mary Birch Hospital have said.

Due to serious pregnancy complications (in this case, pre-eclampsia – a condition that can be fatal for woman and child), Saybie's mother was admitted to the hospital for an emergency C-section at 23 weeks and 3 days gestation in the womb.

While a premature birth refers to any that takes place more than three weeks before the due date, Saybie was what is called a micro preemie. That is an infant born before 28 weeks' gestation – i.e. 12 weeks earlier than a typical pregnancy, which ends after 40 weeks. 

Even for a preemie, Saybie was tiny, weighing half as much as a normal 23-weeker and about as much as a large apple. But unlike many infants born before the 28-week mark, she didn't suffer from any of the typical complications. These can include brain bleeds and problems with the lung and heart, the hospital says.

Now, after a five-month stint in the hospital, baby Saybie weighs 2.5 kilograms and has been allowed home.

Sharp HealthCare

Preterm births make up 8 percent of babies born in the US and Canada, and thanks to improvements in healthcare, they have a better chance of survival than ever before. 

Evidence collated by the American Psychological Association (APA) suggests that a low birth weight includes certain health risks that extend into adolescence and adulthood, including an increased likelihood of developing certain mental health conditions such as attention deficit hyperactivity disorder, depression, and anxiety. Other research suggests premature infants tend to be less healthy and face a greater risk of heart health problems in adulthood – but loving and supportive parents as well as nurturing school environments can help mitigate the effects. The research, presented at the Eastern Nursing Research Society in 2011, also found that premature babies tend to be resilient with a strong drive to succeed.