(Cover) - EN Showbiz - Mariah Carey has compared performing at altitude to giving birth to twins.

The 42-year-old star is currently in Austria, where she was taking to the stage in Ischgl to mark the end of the ski season. Her show coincides with her twins Monroe and Moroccan turning one. Mariah has taken to her Twitter account to recall the labour process.

"Singing at this altitude is almost like giving birth to twins, which I did last year on this day.. lol! Happy birthday dembabies!!(sic)" Mariah wrote.

The star was clearly overwhelmed at the reception she received during her trip to Austria.

She praised her loyal supporters for turning out to welcome her.

"Thank you to all the fans who came out to the show! I hope you liked Underneath The Stars which I did especially for the lambs.. LYM! (sic)," she tweeted.

Mariah has had a busy time of late. As well as celebrating her children's first birthdays and preparing for a live performance, she has also renewed her vows with husband Nick Cannon.

The couple looked like newlyweds as they re-affirmed their commitment to each other on the Eiffel Tower in Paris on Friday.

Mariah looked stunning in a white fishtail gown with a black sash. She also wore a 200,000 diamond necklace complete with matching earrings.

Nick, 31, complemented his wife in a white suit and black tie.

Mariah and Nick wed in a private ceremony in the Bahamas in 2008. (C) Cover Media