Chris Pizzello / Invision/AP
Chris Pizzello / Invision/AP

It's official: Mel Gibson's girlfriend, Oksana Grigorieva, is pregnant.

The actor confirmed the news during a taping of NBC's "The Tonight Show" With Jay Leno this afternoon (the show airs tonight). He jokingly refers to himself as "Octo-Mel" now that he'll have eight kids.

Gibson's wife of 28 years, Robyn, filed for divorce six weeks ago amidst speculation that Grigorieva, a singer on Gibson's record label, was expecting a child.

According to reports, Grigorieva is in her second trimester and due this fall.

Grigorieva, 38, and Gibson, 53, came out publicly as a couple at the April 29 premiere of "X-Men Origins: Wolverine" in Los Angeles.

The duo became close after Grigorieva was hired to compose a song on Gibson's thriller, "Edge of Darkness," which filmed last summer in Massachusetts.

"They would come out and attempt to walk around separately, but then at the end of the day, they both returned to the same hotel," an on-set source told Us Weekly. "She was there on and off for a week, but it was clear she had no business there other than to be with Mel."

Gibson has been separated from Robyn for nearly three years according to court papers he filed on April 13. They have seven children together. Grigorieva has a son with actor Timothy Dalton.

Gibson -- worth about $900 million -- and his wife have no prenuptial agreement. Their divorce settlement could be the largest in history because, under California law, community property (including income) is divided 50/50.