The former Big Brother housemate turned radio and television identity announced on Thursday she and her partner Chris Saville are expecting a new addition to the family next March.
The Logie award winning presenter told listeners on her breakfast show MIX 101.1 in Melbourne that she has been keeping it secret for four months.
"I'm so excited because it's something we have known in this studio for 18 weeks, but I can reveal I am having my third baby," Swan told listeners.
"I only told my dad last week.
"My second and third are very close together."
Swan and Saville have two sons Leo, 3, and Kit, 15 months.