All eight babies born to a woman in Southern California are breathing on their own and remain in stable condition, doctors said Tuesday.

The mother, who has not been identified, gave birth Monday in Bellflower, Calif., to the six boys and two girls, weighing between 1.8 pounds and 3.4 pounds.

The babies -- identified for now by the letters A-through-H -- are the world's second live-born set of octuplets.

Dr. Mandhir Gupta, a neonatologist at Kaiser Permanente Bellflower Medical Center, told ABC the eight babies "are doing actually very, very well."

Originally, doctors only thought the mother was carrying seven children.

Then, after delivering seven babies in five minutes, doctors were surprised to find an eighth baby.

"It is quite easy to miss a baby when you're anticipating seven," Dr. Harold Henry, chief of maternal and fetal medicine, told reporters Monday.

Henry was one of 46 doctors, nurses and assistants who worked together to deliver the children by Caesarean section.

Two of the newborns initially needed ventilators but their breathing tubes have since been removed.

"Only three babies need some sort of oxygen through the nose right now but they are breathing on their own," Gupta said.

The babies will likely remain in hospital for at least two months but the mother should be released within a week.

The mother checked into hospital in her 23rd week of pregnancy and gave birth to the octuplets seven weeks later.

Doctors would not disclose whether the mother had taken fertility drugs.

The eight children, in the order of their appearance, born at Kaiser Permanente Bellflower Medical Center:

  • Baby A, a boy, weighing 2 pounds, 11 ounces, born at 10:43 a.m.
  • Baby B, a girl, weighing 2 pounds, 12 ounces, born at 10:44 a.m.
  • Baby C, a boy, weighing 3 pounds, 4 ounces, born at 10:45 a.m.
  • Baby D, a girl, weighing 2 pounds, 8 ounces, born at 10:45 a.m.
  • Baby E, a boy, weighing 1 pound, 8 ounces, born at 10:46 a.m.
  • Baby F, a boy, weighing 2 pounds, 12 ounces, born at 10:47 a.m.
  • Baby G, a boy, weighing 1 pound, 15 ounces, born 10:47 a.m.
  • Baby H, a boy, weighing 2 pounds, 11 ounces, born at 10:48 a.m.

With files from The Associated Press