A Melbourne super mum has fallen pregnant with quintuplets without the aid of IVF, Seven News can reveal.

The babies are due to arrive any day and will be the first set of quintuplets born in Victoria in more than three decades.

And as well as becoming a mum to five new babies, the 48-year-old mother has more than 10 other children waiting on the arrival of their new sisters or brothers.

The expectant woman, who did not want to be identified, is in the third trimester of her pregnancy and is due to give birth at Monash Medical Centre in Clayton.

Melbourne's last set of quintuplets were born to Josephine Kissane and her husband, Peter, at the Mercy Hospital in February 1980.

The Kissane quins, four boys and one girl, were delivered by Caesarean section 11 weeks prematurely, and, sadly, none of them survived.

The chances of conceiving quintuplets naturally is about one in 55 million, doctors say.

Obstetrician Dr Len Kliman told Seven News: "Fertility naturally declines and to conceive spontaneously after the age of 45 is uncommon, but to have a multiple pregnancy after the age of 45 is particularly uncommon."

Records dating back to 1967 show 11 sets of quintuplets have been born in Australia.

A team of more than 30 obstetricians, pediatricians and nursing staff are expected to be assembled when the time comes to deliver the five babies.

In 1996, specialists at the Monash Medical Centre delivered the Ranaweera quads.

But the hard work for Niroshan and Veronica Ranaweera began when their four baby sons went home.

Thankfully, the family had great support with a team of volunteers on hand to help with bottle feeds and nappy changes around the clock.

Margaret Pitts is the mother of one of Victoria’s largest families with 12 children, and predicts a very busy road ahead for the quintuplets' mum.

"Good luck to her, I wouldn't like to have five, twins was bad enough," she said.

Margaret, who has three sets of twins, told Seven News the financial cost of raising the children will be overwhelming.

It costs about $1,100 to keep one baby in nappies for one year. It is estimated the annual cost of nappies will top $5,500 for five babies.

When it comes to feeding time, Margaret says the quintuplets' mum may require a few extra helping hands.

"There's always ways you do it with twins, but I don't know with five," Margaret said. "I'm not sure how you'd do that...you'd have to have a couple of extra hands all the time."