Brooke Shields tackles aging and the pressure to remain forever young in new book

“I was doing an Instagram Live and people were saying, ‘I really wish you looked like you used to,’” Brooke Shields tells The Times from her hotel room in Los Angeles.

If Shields is getting criticized about her looks, what hope is there for the rest of us? That’s one of the quandaries at the center of Shields’ latest memoir about aging, “Brooke Shields Is Not Allowed to Get Old.”

“The past books that I’ve written, except for the children’s books, have all been based on one event that was truly traumatic for me, so that was the impetus,” says Shields, who previously wrote books about her postpartum depression and complicated relationship with her manager mother. “This one didn’t have that, so it was a little unnerving for me in the beginning.” But that “made it even more exciting to write — and much more enjoyable to read the audio book.”

Shields wasn’t even sure she wanted to write this book, originally suggested to her by her agent as a continuation of the conversation she started with her podcast, “Now What? With Brooke Shields,” and in keeping with her hair care line, Commence, designed for mature tresses.

The former child star had recently revisited her past in the Emmy-nominated documentary “Pretty Baby,” named for the controversial 1978 movie in which Shields played a young sex worker, and headlined a song-filled, one-woman show titled “Previously Owned by Brooke Shields.”

“Did we really need more of me out there? The documentary was a lot. ‘Do you really need it, Brooke?’ I always get really cringey about that stuff,” she says, channeling her internal debate about embarking on the project.

“But as I was thinking about it, it’s indicative of age to feel this desire and need to look at where I am in my life and look back differently, but don’t stay looking back,” she adds, deciding whether she could “make it funny, irreverent, silly but truthful and have it be positive for women, instead of what we’re taught to fear about age, supported or negated by stats and studies, then that to me would be an interesting read.”

As with Shields’ aforementioned other recent projects, she was primed to consider what this moment in her life meant in the wider context of societal willingness to talk about menopause.

“Not only is this happening to me, but it’s happening to other women,” she points out.

Shields is willing to poke fun at herself — and she doesn’t take herself too seriously, as past comic turns in shows such as “Suddenly Susan” and “Friends” attest. People address the former Calvin Klein model by name on the street, but that same name can also be a rallying cry for her when her confidence has been shaken.

“You’re FBS: F—ing Brooke Shields,” her friends will bolster her at such moments.

There’s a particularly entertaining anecdote in the book about her daughter borrowing her designer clothes. Shields felt they should be saved for a special occasion, to which her daughter replies with the above line — minus the expletive.

Shields once would have objected to such talk about her celebrity or beauty. “I used to go, ‘Oh, God. Stop.’ Because to me it felt like arrogance,” she says, noting that her outsize reputation meant she was perhaps overlooked for more serious roles or that people she wanted to work with had preconceived notions of what she was able to do.

But now she leans into the recognition: It’s allowed her to make a living and gotten her to a point in her career where she’s now the subject of retrospectives and reconsideration — whether by “Pretty Baby” director Lana Wilson or by turning the mirror back on herself.

“I’m not comparing myself to Marilyn Monroe but — and I say it in the book — when someone in the public eye dies at their most youthful and famous, they become immortalized at that age,” she observes. “When you don’t do that,” people can be dissatisfied. “I can’t be this idol anymore because I don’t look like I did in ‘Blue Lagoon’ anymore, or whatever.”

Though there’s much more in “Brooke Shields Is Not Allowed to Get Old,” an apt takeaway is “WWFBSD — What Would F—ing Brooke Shields Do?”