The actress' adopted daughter Dylan welcomed baby Evangeline on Monday (05Sep16), and proud Mia, 71, took to Twitter to share the news with fans, posting a photo of the newborn sleeping hours after her birth.

"Welcome to my beautiful little grand-daughter, Evangeline born 3 hours ago to Dylan Farrow and her husband, Dana," she captioned the shot.

Mia's broadcaster son Ronan was there for the birth and he posted a shot of himself cradling his niece on Instagram with the caption: "Uncle X12."

The Rosemary's Baby star adopted Dylan when she was just two weeks old in 1985, and her daughter hit the headlines in 2014 when she wrote a piece in the New York Times newspaper accusing her adoptive father, director Woody Allen, of sexually abusing her when she was a young girl. Woody has always denied the allegations and has never been charged.

Ronan recently spoke out to support his sister in May (16), admitting he regrets telling her to stay silent on the alleged assault.

"Initially, I begged my sister not to go public again and to avoid speaking to reporters about it," he told The Hollywood Reporter. "I'm ashamed of that, too. With sexual assault, anything's easier than facing it in full, saying all of it, facing all of the consequences...

"I ultimately knew she was right. I began to speak about her more openly, particularly on social media. And I began to look carefully at my own decisions in covering sexual assault stories."