According to Us Weekly, the former Heroes star is expecting her first child with boxer fiancé Wladimir Klitschko.
Hayden has yet to confirm the news.
The 24-year began dating Ukrainian-born heavyweight fighter Wladimir in 2009 after meeting through friends, and Hayden revealed last year that it was their height difference that broke the ice.
"He's huge," she told Ellen DeGeneres. "I know I'm small but he's large. That's how we met. I said, 'You're huge', he said, 'You're tiny'. And that was it!"
Hayden - who currently stars in TV show Nashville - split from Wladimir two years later before rekindling their romance in 2013. An engagement was announced in May that year.
"I've known him since I was nineteen so five years," said Hayden. "It's been a while now. He's a good dude."
She added to Cosmopolitan magazine this year: "We were friends for a year first. On paper, a relationship between the two of us looked crazy. From where we live to where we come from, the differences in our lives are fairly big."
"On the surface, everything about us is unalike. But at our core, our morals and goals in life are very similar, so our differences become a lot less terrifying. I'm in awe of what he does and who he is – that's a very strong feeling. He doesn't let me get away with things; he has the patience of a saint, but he is definitely no shrinking violet."
Congratulations to Hayden and Wladimir!
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!
Got an iPad or iPhone? Reveal Mag is specially designed to fit!
Celebrities who announced pregnancies in 2014 in pictures:
Copyright: WENN Lexie Appleby/Future Image/Bridow/Instagram