The `Hero` hitmaker - who was pictured on stage in Brazil earlier this week with an apparent baby bump - and husband Nick Cannon have allegedly told friends how "overjoyed" they are to be expecting their first child together, despite refusing to publicly confirm the happy news.
A source told RadarOnline.com: "Nick has been telling friends how excited he is to be a dad.
"Mariah has tried so hard to get pregnant. She`s very excited. She wants to wait as close to full term as possible before going public with the news to her fans."
Following her show in Brazil, Mariah - who recently dropped out of her next movie, `For Colored Girls Who Have Considered Suicide When the Rainbow Is Enuf`, citing medical reasons - tweeted she had found the performance tough for "personal reasons".
She posted: "Seriously, I really do love it here, beautiful people inside and out! Tonite was tuff 4 me 4 personal reasons, but U got me thru! L4L. (sic)"
Nick has refused to be drawn on the pregnancy speculation this week, insisting it is a matter for his wife to tell her fans.
He said on his radio show: "I`ve said it before and I`ll say it time and time again - when my wife feels like talking about whatever she wants to talk about, you will hear it directly from her."