The birth of octuplets in California, hailed as a medical triumph by doctors who delivered the tiny infants, has dismayed fertility experts who say high-number multiple births are an outcome they work hard to avoid.

The arrival of six boys and two girls on Monday, marking only the second known set of octuplets in the United States, has sparked intense interest and media coverage, particularly after reports the mother already had six other children.

But experts in reproductive health say an occurrence of octuplets represents a likely case of fertility assistance gone awry, posing grave risks to the health of the mother and her premature offspring.

"The cost of taking care of multiples is huge," said Dr. Vicken Sahakian, director of the Pacific Fertility Center in Los Angeles. "It's not going to finish when the babies go home. There's a high likelihood they're going to have (long-term) medical and psychological handicaps."

For that reason, the U.S. medical establishment has long-standing guidelines designed to reduce the probability of multifetal pregnancies.

A single, healthy baby is the ideal strived for by fertility specialists, said Dr. David Adamson, a fertility specialist and past president of the American Society for Reproductive Medicine.

Even twins can be fraught with complications for mother and babies, but three or more simultaneous births "are considered definitely an undesired outcome," he said.

The arrival of the octuplets, nine weeks premature, was celebrated as a medical success by doctors who handled their birth, but "only from the standpoint of maximizing delivery," said Dr. Mousa Shamonki, director of assisted reproduction at UCLA's medical school.

"Well over 90 or 95 percent of these situations will result in a catastrophic event, namely the loss of many, if not all, the fetuses, and a high risk to the mom," he said. "It's a scenario that really should never happen."

The identity, age and background of the octuplets' mother was withheld for privacy reasons by her doctors at the Kaiser Permanente Medical Center in the Los Angeles suburb of Bellflower.

The woman issued a statement on Thursday saying she was "ecstatic about all of their arrivals." Seven of the infants are breathing unassisted and most have started feeding.

Doctors said the woman came to Kaiser in her first trimester from "an outside provider."

'WHAT IS MAGIC NUMBER?'

Comments from the woman's mother suggested she conceived through in vitro fertilization, in which eggs from the mother are joined with sperm in a dish, and the most healthy-looking embryos are returned to her uterus.

The mother told the Los Angeles Times her daughter had decided not to abort any of the embryos earlier in the pregnancy.

Since guidelines generally restrict the number of transferred embryos to one or two, fertility experts said they doubted she conceived through in vitro with the help of a legitimate clinician.

"Having eight (embryos) implanted is just absurd," Shamonki said. "I can't imagine one of my colleagues doing that."

He said a more likely scenario was that the mother received fertility drugs designed to stimulate ovulation. When the eggs reach maturity, they are fertilized in the mother through artificial insemination or intercourse.

Doctors are supposed to monitor such patients, watching for an over-production of eggs. In such cases, they typically terminate the process and advise the woman not to have sex until another cycle with a lower dose of fertility drugs.

Otherwise, the woman can abort some of the embryos after conception, a process called selective reduction.

Sahakian predicted an "outcry in our profession" from publicity surrounding the octuplets, which he said could lead to calls for regulations to limit the number of embryos that may legally be implanted, as happens in some European countries.

Fertility experts said it was not their role to question why a patient wants to have more children. "Who decides what is the magic number?" Sahakian said. "for some people, two is too many."