Carey Mulligan Felt 'Very Alone and Very Scared' Dealing with Postpartum Depression After Birth of First Baby

Carey Mulligan typically keeps her home life with husband musician Marcus Mumford and their family close to the vest.

But starring in the new movie She Said inspired the British star to open up about her experience coping with postpartum depression after the birth of her first child, the two-time Oscar nominee says in this week's issue of PEOPLE.

In the film, Mulligan, 37, plays New York Times investigative reporter Meghan Twohey, who, with journalist Jodi Kantor (played by Zoe Kazan) published a bombshell Harvey Weinstein investigation in 2017 that would go on to spur a worldwide #MeToo reckoning.

But what most don't know is that when Twohey took up the towering investigation with Kantor, she was on maternity leave coping with postpartum depression.

"One of the parts of the script that of hit me initially the most was Megan's experience with postnatal depression. I had a very similar experience with my first child seven years ago, and felt very alone, and very scared, and also very confused by the whole experience," says Mulligan, who is mom to daughter Evelyn, 7, and son Wilfred, 5.

For Mulligan, "it was really going back to work in some form," shooting the 2015 film Suffragette, "that was the thing that got me on the road to finding myself again with incredible support around me."

The difficult period is something Twohey had not shared publicly prior - not even the 2019 non-fiction tome she co-wrote with Kantor, which provided source material for the new film.

"We don't really talk about our personal lives," Twohey tells PEOPLE. "We just focus on the work." But in its film adaptation, She Said makes a point to show the full lives of the two working mothers as they chased printable proof of Weinstein's sexual misconduct and staved off his legal team's intimidation. For Twohey, it coincided with "one of the most vulnerable periods in my life."

In the early days of the Times investigation, Kantor called Twohey, then more of a colleague than a friend, for advice about approaching Weinstein's victims. What she didn't know was that Twohey was quietly struggling following the birth of her daughter, who is now five.

"I could hear in Megan's voice that something was wrong. And because I had postpartum depression, I suspected it in her," says Kantor, whose daughters are 16 and 7. She swiftly shared a doctor referral.

Twohey ultimately allowed filmmakers to include the intimate moment on camera.

"I thought Megan including it in the film when it was not in the book was just a really wonderful," says Mulligan. "And I wanted to talk about it and say it's horrible, and there's a way through it. There's just so many people who go through it. I think films just always allow a conversation (like this) to start."

The actress hopes the film spurs more open conversation around the condition. "I felt like I was completely on my own when this happened to me," she says. "And actually, so many people have experienced this. Megan has experienced it, and so many of my friends have, and we all feel horrific, like we're the only person who's ever been through it."

Though the reporters say they had no idea what would happen once their work went public - certainly not Weinstein's 23-year conviction of sex crimes in New York, nor his current trial in Los Angeles - She Said ultimately represents "the truth" of the way the Weinstein investigation started, says Kantor.

"It was two women who were leaning on each other really hard to shoulder what felt like overwhelming responsibilities: the responsibility of being a parent, becoming a parent, raising kids, and then the responsibility of trying to unearth these difficult truths," says Kantor. "And when I think back to the summer of 2017, I just think about the weight of both. This feeling of we have to get this story, which is so, so, so hard. We can't fail. And then, we have to get home and get the kids. And you're not really going to allow yourself to fail at that either."

"When we finally saw the film, I was just really moved by it," Twohey adds. " And I think that there's a real chance that even beyond journalists, a lot of working mothers will recognize themselves on the screen and feel seen."

She Said is in theaters now.

For more on She Said, pick up the latest issue of PEOPLE, on newsstands Friday, or subscribe here.