Courtney Love admits to using heroin while pregnant with Kurt Cobain's daughter

Being the daughter of Courtney Love and Nirvana frontman Kurt Cobain must come with its share of hurdles, but Frances Bean Cobain's challenges began even before she was born.

In the new documentary KURT COBAIN: Montage of Heck, which premiered last weekend at the Sundance Film Festival, Courtney, 50, reveals that she used heroin while pregnant with Frances, now 22.

"I used it once, then stopped," Courtney says. "I knew she would be fine."

Though her apparent lack of remorse is surprising, her candor isn't. Courtney's always been blunt and outspoken, and she more or less commissioned the project about her late husband, who committed suicide in 1994 at 27.

"In 2007 [I] got a call from Courtney who wanted a film that went beyond the music," said the doc's director Brett Morgen. "The journey started there. But I made this for Frances. She gave me the keys to go and make the film."

Indeed, Frances was executive producer and provided footage of her early months being raised by her parents.

Both Kurt and Courtney infamously battled heroin addiction during their marriage. Despite his demons, Kurt expressed his desire to be a good dad to Frances.

"My father and I are very different people," he said in archive footage. "I am capable of a lot more affection than he is. I don’t want her to be screwed up."

She seems to have turned out pretty well, though she's been estranged from her mother as an adult. The two reunited at the premiere for the first time in five years.

"So sad yet so uplifting, beautiful and gorgeous," Courtney tweeted of the doc afterwards. "Your daddy would be so proud of you baby. Thank you."