Keio University in Tokyo said Tuesday that after growing up to a weight of 3,238 grams, a baby with a birth weight of 268 grams was released from hospital care and became the world’s smallest boy to be sent home healthy. The previous record holder was born in 2009 in Germany weighing 274 grams, the university said, citing the registry of the smallest babies in the world at the University of Iowa. The youngest girl was born in 2015, also in Germany, weighing 252 grams. According to the Tiniest Babies Registry website, 23 babies worldwide survived after being born prematurely and weighing less than 300 grams, of which only four were boys.

The baby from Tokyo was born through an emergency cesarean section in August as his weight did not increase at 24 weeks gestation and doctors thought his life was in danger, the university said.

The baby was so tiny at birth that he could fit in a pair of hands. But after doctors treated him at a neonatal intensive care unit at the hospital, by managing his breathing and nutrition, he grew steadily and was able to be breastfed. He left the hospital last Wednesday, two months after the initial due date.

Babies born weighing lower than 1,000 grams are likely to suffer heart failure, have difficulty breathing or acquire severe infectious diseases due to their underdeveloped organs.

The survival rate of these babies in Japan and other developed nations has been as high as 90 percent in years past. But the rate plunges for babies, especially boys, born at less than 300 grams.

“I want people to know that babies can return home vigorous even if they are born small,” said attending Dr. Takeshi Arimitsu.