The way this Melbourne mum just gave birth to her enormous, 6kg baby is unbelievable.

An unusually big baby was born at Victoria’s Mercy Hospital on Tuesday.

Baby Brian Liddle Junior weighs 6.06 kilograms (13 pound, 4 ounces), which makes him twice the size of the average Australian newborn. The not-so-little one already fits into size 0 baby clothing and is too big for newborn nappies.

Incredibly, Brian Jnr’s mother Natashia Corrigan gave birth naturally and only received gas to help manage the pain.

Corrigan commends the Mercy Hospital staff for their support during the understandably difficult labour.

“They kept me strong and calm when it seemed like chaos was happening around me,” Corrigan told the Herald Sun. “Because he was so big it was a bit hard to get him out, and they had to get a few extra staff members to come in and help."

When Corrigan was 36 weeks pregnant, she was warned that her baby would be on the bigger side as he already weighed nine pounds. Corrigan went into labour at 40 weeks.

Named after his father, Brian Jnr may be the largest baby born in Victoria. Unfortunately the office of Births, Deaths and Marriages does not keep track of birth weights, so there is no way to confirm this.

At the very least, Brian Jnr is the biggest baby to be born at the Mercy Hospital in Heidelberg.

"In about 11 years [he] is the biggest baby we've had," Mercy Hospital Nurse and midwife Julie Kane told 7 news.

Corrigan has two daughters, but says that she always dreamed of having a chubby baby boy.

“I dreamed of a little fat baby,” Ms Corrigan told 7News. “I’ve always wanted a little fat baby and now I’ve got a big baby.”

Mother and baby are both doing well.

Holly Wainwright and Andrew Daddo discuss all things from understanding your baby’s facial expressions, raising children in tiny apartments, and toilet training, to changing the face of childbirth.