While appearing as a guest on The Morning Show, Erin was asked by hosts Larry Emdur and Kylie Gillies whether she and her husband were planning on having more children.
Erin, 34, and her husband - whose real name is Elliot John Gleave - share a one-year-old son named Evander Maxwell.
When asked on the show, Erin revealed that she had endured a miscarriage just one month ago, describing it as 'heartbreaking'.
'We definitely want another baby... but I sadly had a miscarriage last month,' she said.
'We're totally fine - it's just one of those things that are really really common, and I'm in a really lucky position of already having Van.
'There are so many women out there who have had miscarriages, and they don't get to have a child. It's heartbreaking.'
Erin hopes that by speaking openly about her miscarriage, other women will feel free and unashamed to do the same.'
'For me, I found solace in knowing how common it was, because once I got talking, you realise just how many people are affected by it,' she explained.
'If I could find solace in that and I think if more people spoke about it, then it might not be as tough for people to go through it.
'It's always going to be horrible but you can make it a little bit easier by talking about it.'
Erin and Elliot got married in 2013 in Australia, and added Evander to their family in December 2014.
Soon after Evander's birth, Erin revealed that she 'couldn't wait' to have more kids.
Erin and Elliot met in 2011 while she was interviewing the rapper for an MTV show. After being Miss Universe Australia, Erin is now taking a break from modelling and presenting to focus on being a mum.
'We have an amazing life. We are very lucky,' she carried on later in the interview.
She also claimed that her son 'has the best little Aussie accent.'
Earlier this year, Erin told The Daily Telegraph that 'as soon as you have a baby, you can clearly see the things that you have in your life that you are grateful for.
'It makes you reassess your priorities.'