A 32-year-old woman in Arizona gave birth to sextuplets Monday.
"We anticipated all possible problems, and they didn't happen," Dr. John Elliott, one of three doctors who delivered the babies, said in a statement. "This delivery (was) as good as you could possibly draw up."
The Masche sextuplets were born prematurely after 30 weeks and four days. All but one weighed less than 3 pounds (1.4 kilograms).
Dr. Jordan Leonard, who is overseeing care of the Masche sextuplets at Phoenix Children's Hospital, said the sextuplets appear to be in stable condition.
"We're very pleased with how they're doing," Leonard said.
Their tiny lungs are underdeveloped, Leonard said, and five of the six were on ventilators Monday to help them breathe.
Leonard said he expects all of them to be off the breathing machines after a day.
New father Bryan Masche, 29, said in an interview with The Associated Press last week that the couple was terrified when they learned in December they were going to have six babies.
The couple had tried for years to conceive naturally before turning to artificial insemination, he said. In addition to artificial insemination, Leonard said Jenny Masche used medication to stimulate her ovulation cycle.
"We're blessed and excited," Bryan Masche said.
The chances of spontaneously conceiving sextuplets is one in 4.7 billion, although the odds improve significantly when fertilization treatment is used, said Dr. Helain Landy, the chair of Georgetown University Hospital's Obstetrics and Gynecology Department.
The couple have named their babies: Bailey Elizabeth, Savannah Jane, Molli Grace, Cole Robert, Blake Nickolas, and Grant William.
Once home in Lake Havasu City, Arizona, the babies will sleep two to a bed in three matching cribs.
Right now, their room is so full of donated baby supplies that the door barely opens, Bryan Masche said last week. "We're still deciding whether to paint the room pink and blue or just pink or blue, or what."