Mel Gibson's girlfriend is reportedly pregnant.

The 59-year-old actor - who already has seven children with ex-wife Robyn and daughter Lucia, five, with ex-girlfriend Oksana Grigorieva - is said to be expecting his first child with girlfriend Rosalind Ross, who he has been dating since July.

An insider claims the 24-year-old former equestrian star-turned-aspiring screenwriter sparked speculation among her friends when her behaviour changed a month ago.

The source explained: ''Rosey suddenly gave up drinking about a month ago. And while she won't admit she's pregnant, she's not denying it either.''

And if Rosalind - who met the 'Braveheart' star when she applied for a job at his production company Icon - is pregnant, it could be the first of many children for the couple.

The source added to Australia's New Idea magazine: ''[Rosey's] always said that she wanted to be a young mum and have three or four children.''

Rosalind is Mel's first girlfriend since he split from Oksana in 2010, and since they got together, they have enjoyed spending time together away from the public eye at both his estate in Costa Rica and on vacation in Panama.

A source said recently: ''It's clear the two of them are really happy together...Mel hasn't had the best luck with the ladies. He's in no rush to turn his relatively new romance into a high-profile affair.''