A Japanese baby believed to be the smallest surviving boy ever when he was born at 258 grams in October, left Nagano Children's Hospital Saturday after growing to seven pounds. File photo by Praisaeng/Shutterstock

April 20 (UPI) -- A Japanese baby believed to be the smallest surviving boy ever when he was born at 258 grams in October, left Nagano Children's Hospital on Saturday growing and healthy.

Ryusuke Sekino was born the equivalent of 9.1 ounces six months ago. Doctors weighed the toddler in at 3.37 kilograms, or 7.42 pounds. His birth size set a world's record for the smallest surviving boy.


"After going home, I want the baby's brothers and sister to hold him in their arms," Toshiko Sekino, the boy's mother, said. The family lives in Karuizawa, Nagano Prefecture, but spent plenty of time at the Nagano Children's since Ryusuke's birth.

Doctors admitted Toshiko Sekino to the hospital Sept. 29 after suffering from hypertensive disorders in connection with the pregnancy. Two days later, she delivered Ryusuke via emergency cesarean section, 24 weeks and five days into the pregnancy, Asahi Shimbun reported.

Ryusuke, who had been cared for in the hospital's neonatal intensive care unit, beat the previous world record holder Shinjuku Ward, who weighed 268 grams last year after being born in Tokyo.

The boy's environment was controlled the entire time for temperature and humidity and ate through a stomach tube. Ryusuke also managed at times to get his mouth around a cotton swab soaked in breast milk. The nutrition helped the boy pack on the pounds.

"I was not expecting to be able to see him outside the hospital this quickly," the boy's father Kohei Sekino said.