Erin McNaught's 9-month-old baby had brain surgery this week. She's just shared an update.

Australian actress, model and presenter Erin McNaught has shared an update about her nine-month-old son, Obi Brooks Kotaras's health battle, days after announcing that he has been diagnosed with a brain tumour.

Obi is McNaught's first child with partner, Stace Cadet, a dance producer, whose real name is Stasi Kotaras.

In an update over the weekend, McNaught shared a photo of her kissing little Obi's chest as he lay in a hospital bed with a bandaged head.

"Today Obi had the surgery to remove the tumour. The amazing team here are very happy with the way it went," she wrote on Instagram stories on Saturday, Channel Nine reports.

"While it's too early to tell much more, we are hoping this will have been his biggest hurdle."

She said the family are "taking each day as it comes, but oh so thankful for today."

"Thank you everyone for all your beautiful messages of support. They mean more to us than you will ever know!"

The surgery comes just days after the parents shared Obi's condition with their followers.

The couple said they noticed a "rapid decline" in Obi's behaviour and happiness over the last few weeks in a post shared on Instagram.

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A post shared by STACE CADET (@stacecadetmusic)

"He was having problems eating, sleeping and most recently, keeping his head straight," they wrote.

"Late on Tuesday, as a precaution, we took our little man in for an MRI under instruction from our Doctor. At about 6:00pm Tuesday night we met with a neurosurgeon who broke the heartbreaking news that Obi has a large brain tumour on the right side of his brain.

"We are absolutely shattered and the last few days have been our hardest days."

Obi is being treated by a team at Queensland Children's Hospital, and his parents are optimistic about his prognosis.

"Our team at the Queensland Children's Hospital have been incredible and we remain hopeful that we can remove the mass and get Obi healthy and happy, pending the results," they shared.

"We have a long and difficult road ahead us but are so lucky to have our family and friends' support at this time and we're keeping focussed (sic) on getting our little boy back."

McNaught, 43, is former Miss Universe Australia. She started dating Cadet in 2023.

Obi was born in October.

Erin shares two children, sons Evander and Ennio, with her ex-husband Example, a singer whose real name is Elliot John Gleave.

Image: Instagram/@stacecadetmusic and mcnaughty.