Melbourne family welcomes 6.3kg baby, almost double the weight of an average newborn

A baby boy has smashed record for the biggest baby born at a Melbourne hospital, coming in at almost double the weight of a normal newborn.

At 35 weeks Maoama Ala was estimated to weigh 4.5kg, but when he was born on Tuesday at 39 weeks he actually weighed 6.3kg (13.9 pounds).

Measuring 60cm long, Maoama is already too big for newborn clothes, and is wearing onesies made for babies aged three to six months.

"The main thing was not his size, but he was coming out a healthy and happy baby," mum Teuaililo Ala told 7 News.

Obstetrician Dr Lauren de Luca said the newborn's size was "off the charts", and too much to have a safe natural birth.

"Once she knew we were expecting such a big baby, she did decide for an elective [caesarean], which is a sensible option," she said.

Maoama is the fourth child for Ms Ala and her husband, joining nine-year-old twins and a six-year-old brother.

His size hasn't put Ms Ala off having more children though, she's already planning he fifth baby.