A baby weighing just 268 grams at birth, touted as the "smallest boy" in the world, has been released from hospital in Tokyo, after growing to a weight of 3,238 grams in an advance that offers hope to babies with very low birth weight.

According to the Keio University in Tokyo, the boy was born through an emergency caesarean section in August as his weight did not increase at 24 weeks gestation and doctors determined his life was in danger, The Japan Times reported on February 27. "I want people to know that babies can return home vigorous even if they are born small," Takeshi Arimitsu, who treated the extraordinary baby, was quoted as saying at the university's hospital.

The baby was so small 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, weighing 3,238 grams, the report said.

Babies born weighing below 1,000 grams are likely to suffer heart failure, have difficulty breathing or acquire severe infectious diseases due to their underdeveloped organs. The previous record holder was born weighing 274 grams in Germany in 2009, the university said, citing the University of Iowa's registry for the world's tiniest babies. The smallest girl was born weighing 252 grams, also in Germany, in 2015. There had been 23 babies worldwide who survived after having been born prematurely and weighing under 300 grams, out of whom only four were boys, according to the Tiniest Babies Registry website.