Medical team describe a 'successful' delivery
All eight octuplets born prematurely in the US are breathing on their own after ventilators were removed from three who initially had breathing problems.
The six boys and two girls were doing "very, very well", Dr Mandhir Gupta told ABC's Good Morning America.
The babies, expected to be kept in incubators for several weeks, were being fed breast milk via tubes.
However, the unidentified mother intends to breastfeed all eight when they are bigger, Dr Gupta said.
The siblings, who were nine weeks premature, were delivered by Caesarean section in a hospital near Los Angeles, California, on Monday.
The babies weighed in at between 1lb 8 ounces (820g) and 3lb 4oz (1.47kg)
Dr Gupta, a neonatologist at Kaiser Permanente Bellflower Medical Center, said: "Only three babies need some sort of oxygen through the nose right now but they are breathing on their own."
However, he said there was still a possibility that any one of them might need a breathing tube again.
Initially the babies will be fed breast milk through a tube, but as they get bigger "it is quite possible that the mother can breastfeed all eight of them," Dr Gupta said.
US first live-born octuplets delivered in Texas, 1998; seven survive
Octuplets born in Italy, 2000; two die shortly after delivery
Octuplets born in Mexico City, 1967, but all died within 14 hours, according to Encyclopedia Britannica
World's first surviving set of septuplets born in Iowa, US, 1997
First all-female surviving sextuplets born in the UK, 1983, to the Walton family
Hospital medics said that at least four of the babies could be ready for their first oral feeding later on Tuesday.
Asked about the moment when an unexpected eighth baby was found in the uterus, Dr Karen Maples said: "That was a tremendous surprise."
"The baby seemed to be quite high in the uterus, possibly behind another baby, but basically we were just like 'there's one more baby here, are you ready?' And the team was."
Dr Maples said that when the mother heard about the eighth baby she said, "Where was it? Where was it hiding? She was just as surprised, obviously, as all the members of the team."
The babies were delivered by the team of 46 doctors, nurses and assistants in the space of five minutes.
The hospital has declined to say whether the mother became pregnant through fertility treatments, which make multiple birth more likely.
The mother, who did not want more information about the birth released, became just the second person recorded in the US to have delivered a set of living octuplets.
The last octuplets known to have survived birth in the US were born in Houston in 1998. One of the babies died one week later.
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