Rihanna congratulates pal Amber Rose as she announces arrival of baby Sebastian

The 29-year-old and fiancee of Wiz Khalifa revealed they'd welcomed their first child Sebastian Taylor Thomaz into the world on Thursday.

 Amber hit Twitter, telling fans: "Happy Birthday to our baby boy Sebastian "The Bash" Taylor Thomaz! I'm so happy u guys I fell in love all over again! :-)."

And Rihanna sent a cute reply soon after, jokingly adding that their new baby boy had been born just at the right time. 

She tweeted: "Congratulations to my fam @mistercap and @muvarosebud !!! Welcome baby Bash! You're born in an exquisite month #babypisces."

Wiz and Amber - who have been engaged to be married since March last year - announced they were expecting their first child together back in September 2012.

Congrats!  http://www.youtube.com/watch?v=nQ50t8SUxQ0

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