Mel Gibson and Oksana Grigorieva
Albert L. Ortega/WireImage; Richard Young/Startraks
11/01/2009 AT 04:00 PM EST
Mel Gibson may be a father for the eighth time: His girlfriend
, musican Oksana Grigorieva, gave birth to a baby girl, according to reports circulating on the Web. PEOPLE is currently attempting to confirm the news.
The baby, who was due in December, arrived Friday, says RadarOnline.com
Gibson, 53, has seven children (six sons and a daughter) with his estranged wife Robyn, while Oksana has a son, Alexander, with her former boyfriend, actor Timothy Dalton.
"I have a 12 year old, so I've been a mother for 12 years – and of course, there is no first time mother's trepidation as such," Grigorieva, 39, said
on a British TV show in September. "So naturally it's more relaxed, and I'm very dynamic so the pregnancy falls into my work schedule."
In terms of her relationship with the actor-filmmaker, she said, "Actually we have no plans to marry whatsoever. I haven't thought about it – we haven't spoken about it."
In April, the actor's wife of 30 years, Robyn, filed for divorce
. Later that month, he and Grigeorieva made their first public appearance
together as a couple.