The Mad Max: Fury Road actress took to Instagram on Thursday (09Feb17) to share the exciting news with fans.

"Very happy to share that Jason and I are expecting!!" she wrote in a caption attached to a photo Jason took of herself flaunting her large baby bump while sporting a bikini on the beach.

The 29-year-old first sparked rumours she might be expecting last month (Jan17) after she posted a photo on social media that appeared to allude to a pregnancy. In the photo, she is seen wearing uncharacteristically baggy clothing while petting a horse, and she added the cryptic message: "Here's to fresh starts and exciting prospects for the new year. Wishing everyone a happy and healthy 2017".

Many fans quizzed Rosie in the comments section of the image, asking if she was pregnant.

She and movie action man Jason have been dating since 2010 and they became engaged last year (Jan16).

Both stars have previously spoken about how much they love each other and Rosie has been chatting about her desire to have children for years.

"Having a family is something I think about for sure, and whether I'd live here in America or in England (to raise the child), but it's not always as simple as that," she told the UK magazine Express in 2015. "I have no idea what will happen but it'll be interesting to find out, right?"

Furious 7 bad guy Jason, 49, has previously praised Rosie for being his rock, adding, "I think behind every successful man there’s a stronger woman that’s responsible for almost every good thing we do,” he said to Total Film around the time of his engagement to the actress.