Greta Gerwig on Lady Bird's perfect Rotten Tomatoes score

"It's astonishing, it really is. I've nothing to say to it that's eloquent - it's amazing."

That's Greta Gerwig's reaction to Lady Bird, her directorial debut, getting a 100% score on reviews site Rotten Tomatoes - making it the most well-reviewed film in the site's history.

Not that she reads reviews when she has a film out (her acting credits include Frances Ha, Jackie and No Strings Attached), saying to do so is "a little terrifying".

She is aware, though, that Lady Bird, which stars Saoirse Ronan as a teenager navigating her final year of high school in Sacramento, has been widely praised.

"The fact is, we put so much love into it, everybody who made it," she tells the BBC.

"There's such a feeling of pouring your heart and soul into it - from the actors to the crew, to the creative team, and it feels to get that back from the audiences and the critics.

"It's what you hope happens, but you would never expect it to happen."

Gerwig says the positive reviews make her worry people will get inflated expectations for the film, but adds: "At the same time, it is also a movie - it's not a rocket ship to the moon! But mostly, it's just lovely."

The 34-year-old has previously co-written screenplays including Mistress America and Frances Ha, in which she also starred. More recently she's been seen in the Oscar-nominated films Jackie and 20th Century Women.

"I always wanted to be a director, but I didn't go to film school," she says. "I used all the time on set as an actor, and also a co-writer and producer - that's my film school. It was a sort of cobbled together over 10 years of working in movies."

She says she was nervous about showing the film to Ronan and co-star Laurie Metcalf who, as mother and daughter, portray the film's central relationship.

"They gave me everything they had," she explains, saying she felt a responsibility to honour their performances.

Now, as well as being well-reviewed, Lady Bird has already picked up a handful of awards and is tipped for more - including Oscars and Golden Globes.

"I'm very nervous - I'm knocking wood. Of course I would love it if the film was rewarded but Saoirse and Laurie - I just want them to be given props for what they did. It's mostly just exciting. But you can't help it, you do get nervous.

"At awards shows, you're not supposed to care - but really, who are we kidding? Why wouldn't we care?"

Asked about speculation she could become only the fifth woman to get a best director nomination at the Oscars, she says she wants Dees Rees to get a nod for the period drama Mudbound, "so it would be five and six".

"It was a very big moment for me when Kathryn Bigelow won her Oscar for best director, and it was the first time a woman had won," Gerwig says.

"As much as that is not the work, and the work is the thing that's important, visibility and recognition is a big deal for someone like me at home.

"I would be thrilled if - and I'm not just saying this - any women were nominated. And there's a slew of great female directors this year. There's a lot of women who contributed a lot to cinema this year, and I would like to see one of them on that list."

Gerwig will have to wait a few more weeks until the Oscar nominations are revealed to find out who does make the cut - and, indeed, if it is her.

Lady Bird is released in the UK on 23 February.

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