TOKYO • The world's smallest baby boy, who was born last October in Japan weighing as much as an apple, is now ready for the outside world, his doctor said yesterday.

Ryusuke Sekiya was delivered via emergency caesarean section after 24 weeks and five days of pregnancy as his mother Toshiko experienced hypertension.

At 258g, he was even lighter than the previous record holder, another Japanese boy who weighed just 268g when he was born last year. That baby was discharged from a Tokyo hospital in February.

When Ryusuke was born on Oct 1 last year, he measured 22cm in length, and medical staff kept him in a neonatal intensive care unit. They used tubes to feed him, sometimes taking cotton swabs to apply his mother's milk to his mouth.

Nearly seven months later, the boy has grown 13 times in weight, now weighing over 3kg.

He will be released from Nagano Children's Hospital in central Japan at the weekend.

"When he was born, he was so small, and it seemed as if he would break with a touch. I was so worried," his mother told reporters.

"Now he drinks milk. We can give him a bath. I am happy that I can see him growing," she said.

The smallest surviving girl was born in Germany in 2015 weighing 252g, according to a registry put together by the University of Iowa of the world's tiniest surviving babies. For such tiny babies, the survival rate is substantially lower for boys than for girls.

AGENCE FRANCE-PRESSE