Poor Nicole Kidman. She’s become the poster girl for How Botox Can Go Bad.

In “Rabbit Hole,” though, you can see why she’s become so linked with the whole trend of Botox-ed actresses. Kidman plays a mother mourning the loss of her 4-year-old son, yet the actress’s face is physically incapable of crumpling into grief. It stays stubbornly smooth. While her character is howling in anguish, her face remains an opaque mask.

The thing is, despite her rep, Kidman is far from the only female actress to see her emotional range shrink as she’s tried to eradicate wrinkles from her face. She’s among the most noticeable, but a lot of actresses of a certain age can no longer realistically do a weeping scene. Anguish means screwing your face into a storm of wrinkles and blotches, complete with furrowed brow and scrunched-up forehead and puckered crow’s feet.

Watch 2008’s “The Women,” and you’ll notice the scene in which Meg Ryan’s character break down in sobs. Director Diane English shoots that sequence from far, far away. Like, outside a window, looking in. Coincidence? Directorial choice? I suspect it’s necessity — a sleight-of-hand distraction.

In “Rabbit Hole,” director John Cameron Mitchell shoots the scene of Kidman watching in horror as her son is hit by a car as a compendium of partial angles — half her face here, a wisp of her hair there. It could be that he wanted to be artsy ... or it could be that that was the best way to convey horrified emotion from someone whose face doesn’t move much.

Kidman finally fessed up to having done Botox. (This is akin to Jose Canseco admitting to doing steroids; in other words, “Duh!”) But Kidman sounded disingenuous when she told Marie Claire U.K., “I tried (Botox), I didn’t like it, so I’ve gone back to my own forehead. But I’ve never had plastic surgery on my face. People say I have but I haven’t.”

First off, that smooth, icy surface is not any 43-year-old’s natural forehead. Second, she might not have had plastic surgery, but she clearly has used fillers of some kind on her cheeks and lips, at the very least.

Of course, male actors don’t feel compelled to do this. It’s the sexist nature of the world — and, even more intensely, of Hollywood — that women are perpetually supposed to try to look as though they’re in their 20s.

TV actresses are victims of that as much as film actresses are. “Desperate Housewives” is notorious for its actresses looking as though they’ve had too much fun with fillers and Botox. Even younger actresses are starting early on both wrinkle-removers, which ultimately leaves them unable to be expressive. And isn’t acting supposed to be about being expressive?

What do you think of this continuing trend of actresses overdoing Botox?