The nation’s biggest-ever newborn baby will mark his 50th birthday tomorrow, Australia Day.

West Kempsey resident Stephen Lyttle tipped the scales at 16lb 5oz (7.399kg) in Kempsey Hospital on January 26, 1963.

Today, he stands a relatively regular 1.86m and weighs a proportionate 97kg.

“There was someone born in Western Australia two or three weeks before me who was 16lb 2oz (7.314kg),” Stephen says.

“I was born a week early.

“My (older) brother Desmond was 13lb 10oz (6.18kg).

“I’m glad I grew upwards, not outwards.

“I’m roughly the same weight now I was when I was 21.”

His mother, Mary Josephine (Clarke) Lyttle, suffered gestational diabetes while carrying Stephen and Desmond.

It’s a conditition often associated with heavier birth weights.

“I wore size two clothes when I was newborn,” Stephen says.

“By the time I was a year old, I was 34lb (15.422kg). I have a certificate from Guinness World Records.”

He was the youngest of Mary’s 11 children, six of whom are half-brothers and three of whom are half-sisters, with a 25-year gap between the oldest son and Stephen.

“She was a brilliant mum,” Stephen says.

“I adored her.”

He is the father of two sons, born nearly four years apart. 

Older son Jacob will be 24 years old next month and Lachlan is 20. Both were 8.5 pounds (3.856kg) at birth, born on Monday, and were wheeled out of Kempsey Hospital while it was being renovated.

The bouncing babies combined weighed just a few hundred grams more than their dad.

Stephen, who was a felt hatter at the Akubra factory for 29 years, no longer works because of  a sciatic nerve problem.

Tomorrow will be just another day, as far as he is concerned.

“I’m not one for birthdays,” he said.

“I didn’t celebrate my 18th, 21st or 40th birthdays.

“The best thing about being born on Australia Day is that I always get a day off.”

Stephen suspects his sons might have other ideas about marking this latest milestone.