Sean announced the news via Instagram sharing a sonogram of their bub.
‘We’ve got some really exciting news that we are so blessed to be sharing - a special new addition will be joining our splendid blended family in 2019 and we are just beyond thrilled 😁,’ Sean captioned the post.
But the baby news turned out to have a slight twist in the tale as the reality TV star added: ‘We are over the moon to have received a positive 45-day test for our favourite mare to Australia’s leading first season sire - Better than Ready!
The Queensland farmer and Roslyn are keen horse racing fans with their engagement taking place in November at the Flemington Racecourse.
Sean announced the happy moment via Instagram with a picture of a pink rose with the ring inside it.
'Melbourne cup day. @roslynbuerckner said yes,' he wrote.
'Couldn't ask for a better day and how it all come together . Its a story in itself what the day means. There is so many people to thank you all know who you are. In keeping the secret and helping the day come together.
During an interview with A Current Affair last year, Sean admitted he had found the one.
“There’s no need to be on reality TV to find a wife. I think I’ve found one here,” he confessed.