baby boy born prematurely last summer and weighing just 9.45 ounces -- smaller than a man's hand --was sent home last week from Tokyo's Keio University Hospital two months after his actual due date, according to news reports.

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After discovering the fetus wasn’t gaining weight, doctors delivered the tiny infant last August by caesarean section at 24 weeks gestation.

The baby remained in the intensive care unit until he reached 7 pounds on Feb. 20 and was sent home, the BBC reported.

"I am grateful he has grown this big because, honestly, I wasn't sure he could survive," the baby's mother told Reuters.

Citing the Tiniest Babies registry at the University of Iowa, Reuters reported that the previous record was held by a German boy born in 2009, who weighed 9.6 ounces, and a German girl born in 2015, who weighed just 8.8 ounces.

The Japanese baby has not been added to the registry yet.