She said hospital doctors had told the octuplets’ mother that she could reduce the number of embryos to give the ones that remained a better chance of survival: “But she refused to have them killed,” she said. “That is a very painful thing.”

She acknowledged the immense financial and logistical strain of raising 14 children. Aside from the octuplets, the others are aged 7, 6, 5, 3 and 2. The youngest are twins, suggesting that the mother had undergone IVF treatment before.

“It’s going to be difficult,” said the grandmother, adding that the octuplets’ grandfather, Ed, is returning to Iraq, where he will work as a contractor to help support the family.

One report has claimed that the grandfather is an Iraqi national. Approached by press outside his house, he warned that the family would go into hiding after the octuplets are released from hospital. “We have a huge house, not here,” he said. “You are never going to know where it is.”

It took a team of 46 doctors and nurses at the Kaiser Permanente Medical Center in the Los Angeles suburb of Bellflower to deliver the octuplets – six boys and two girls – by Caesarean section. The eighth was a surprise.

The babies were born nine weeks early and although all of them are said to be doing well, doctors say they still face difficulties, including the risk of lung, brain and intestinal problems, or severe disability such as cerebral palsy.

Last night the babies were in the hospital’s neonatal intensive care unit. Five of them were feeding and six were breathing unaided. Asked at a news conference whether medical ethics might have been breached, Harold Henry, a member of the delivery team, replied: “Our patient was counselled regarding her options for pregnancy. The options were to continue the pregnancy or selectively abort.

“The patient chose to continue the pregnancy. Our goal is to provide the best possible care for our patients, no matter what the situation.”

Since the 1980s, when IVF treatment became available in the US, the percentage of twins and triplets as a proportion of total births has increased several-fold. Meanwhile, celebrity couples, such as Brad Pitt and Angelina Jolie, have helped to glamorise the idea of large families.

In one notorious recent case, a Missouri couple faked the birth of sex-tuplets to receive attention and charitable donations from neighbours.

Yesterday, R. Dale McClure, president of the American Society for Reproductive Medicine, confirmed that an investigation had started, but declined to comment further.

He added: “While we are pleased that all eight babies and their mother appear to be doing well . . . the occurrence of high-order multiple births is not a desirable outcome.

“Over the last decade, we have worked diligently to reduce the number of high-order multiple births resulting from IVF treatments. We have produced guidelines restricting the number of embryos transferred during IVF. Published research confirms that these guidelines have led to fewer embryos being transferred and a marked reduction in multiple births. At this point, we do not know the circumstances surrounding the conception of these children and if any medical treatments were involved. If this resulted from an IVF treatment, we can say that transferring eight embryos in an IVF cycle is well beyond our guidelines.”

The father of the world’s first recorded set of octuplets born alive, yesterday offered the new eight-sibling family some advice.

Iyke Louis Udobi, whose wife Nkem Chukwu gave birth to six girls and two boys in Houston in 1998, said the new parents would need community support and “a lot of diapers and milk”.

“Most of the time, [it’s] really, really loud, because eight people are talking, wanting to be heard,” he added.

Mrs Chukwu said: “It initially was overwhelming. But now we’re getting used to it.” The couple’s smallest baby, who was born at 10oz (292 grams), died a week after being born.

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