The second set of live-born octuplets in the US were all breathing on their own on Wednesday, 48 hours after a woman gave birth to the surprising bunch in Southern California.

Three of the babies were still receiving oxygen through a tube in their nose, but they were inhaling and exhaling on their own, the hospital said. All the newborns were expected to have the tubes removed soon.

"They're doing amazingly well," said Socorro Serrano, spokeswoman for Kaiser Permanente's Bellflower Medical Center, where the babies were born nine weeks premature.