Westlife star Mark Feehily just revealed that he's expecting his first baby!

Mark Feehily is to become a father for the first time.

The Westlife singer turned 39 this week and marked the occasion by sharing the news with his fans that he and his fiance Cailean O'Neill are expecting a baby together.

Alongside a photo of the couple with a baby outfit and their ultrasound picture, Mark wrote on Instagram: "Thanks for all the Birthday wishes everyone!!

"It really makes this my most special birthday EVER to let everyone know that later this year we will become Dads for the first time. This is the proudest moment of our lives and we are beyond excited to say it out loud! M&Cx (sic)"

The Flying Without Wings singer's bandmates are equally thrilled by his news.

Shane Filan - who has children Nicole, 13, Patrick, 10, and Shane Jr., nine, with wife Gillian - shared his pal's photo on Instagram and wrote: "So happy for you both. Can't wait for Westlife baby number 10 to arrive."

His wife also shared the picture and added the caption: "So truly happy for these 2 guys ... so in love and exciting times ahead ..(sic)"

Kian Egan - who has sons Koa, seven, Zekey, four, and Cobi, 14 months, with wife Jodi Albert - wrote on his own Instagram post: "Such huge excitement here today! Not only is it @markusmoments birthday but then for him and Cailean to share there news that THEY ARE HAVING A BABY! Aggggggggggghhhhhhh... you gotta love this Westlife family! 10 Westlife babies now!!!(sic)"

Jodi posted: "Another Westlife cousin to join the Westlife family!!! I'm so happy I could burst.. we are all so proud and happy for you guys.. but you already know that !! More celebrations !!! Love you both so much!!! (sic)"

Fourth member Nicky Byrne - who has twins Rocco and Jay, 12, and Gia, five, with wife Georgina - has yet to comment on the happy news.

- Bang! Showbiz