Melbourne baby elephant on the way

Melbourne Zoo's Asian elephant Num-Oi is up the duff.

A leading artificial insemination expert was flown in from Germany to perform the procedure back in August and keepers have been waiting with bated breath for the good news.

"We are so excited. She will be a wonderful mum and it's terrific for our herd to have another young baby," Melbourne Zoo director Kevin Tanner told reporters on Thursday.

An ultrasound, performed two days ago, confirmed the news with a tiny bundle of cells visible in the depths of Num Oi's mammoth uterus.

Trail of the Elephants manager Dominic Moss said the keepers had a suspicion Num-Oi was pregnant.

"All the keepers on the section noticed subtle little nuances with her behaviour and several little quirks like laying down while eating and funny moods," Mr Moss said.

But it's a long distance relationship for Num-Oi with her baby's father Silup hailing from Perth Zoo.

Zoo head vet Dr Michael Lynch said it was important the herd had new genetic contribution, with all other calves fathered from Melbourne's bull Bong Su.

Num-Oi is a second-time mum but she tragically lost her first calf Sanook last year when the 11-month-old became entangled in a tyre and died.

"She did lose a calf last year and our reproductive biologist and our vet team said that it would be good for her welfare to get pregnant again as soon as possible," Mr Tanner said.

But with a gestation period of 22 months, it will be a long wait before Num-Oi welcomes her new calf.