Kim Brooks is a modern-day, middle-class mom, which is to say: She worries about getting it right. As her own mom described her over a game of bridge: “She worries about the kids. She obsesses over them. Speech therapy, occupational therapy, social therapy. If they had any more therapy, they’d be in an institution.”

Her mother added that Kim also swore by co-sleeping, mommy-and-me classes and “baby monitors all over the house.”

And yet.

One day, Kim decided for a few brief moments not to obsess about her kids’ safety and development. She let her 4-year-old son wait in the car for five minutes on a mild March day while she ran an errand. An onlooker saw the child unattended, videotaped this “crime” and called 911. Kim was arrested and charged with contributing to the delinquency of a minor, as if she had bought him a beer.

That is where Kim’s engaging, enraging, terrific book, “Small Animals: Parenting in the Age of Fear” (Flatiron Books), out Tuesday, begins — with her dawning revelation: Somehow, society has decided that if you’re a mom and you have any time left for yourself, you’re doing it wrong. You’re dangerously slacking. And by making motherhood into a multipart, monumental, potentially criminal activity, we have sapped every last ounce of energy from any mom ever hoping to get ahead — all in the name of “safety,” which, of course, is sacrosanct.

The shame Kim felt about the charges was uterus-deep. When pregnant, she’d foresworn all alcohol, cold cuts, sushi. She read all the books. Once the kids arrived, she tried to do everything right. Now she had the “Scarlet A” on her chest: Arrested for doing something almost all our moms did back in the day without a second thought.

A friend suggested Kim call me, because I write about this particular issue all the time: parents harassed for being rational. And so we discussed, really, what had she done wrong?

Kids don’t die of hyperthermia if they wait briefly in the car on a mild day — they die when forgotten in the heat for hours. As for the possibility of a kidnapping, the odds are infinitesimally small. Yet we pretend people like Kim have truly endangered their kids. How come?

To answer that, Kim set out to talk to other moms who have been through the same fire, including Julie Koehler, a suburban Chicago mom arrested for letting her daughters wait in the van while she ran into Starbucks for three minutes.

For this, she was required to have them medically examined for abuse. She also spoke to Debra Harrell, a South Carolina mom who let her 9-year-old play at the local sprinkler park for three summer days while she worked her shift at McDonald’s. For this “abandonment,” Harrell was thrown in jail overnight and lost custody of her daughter for 17 days.

Why were these normal moms considered criminals, Kim wondered, when, say, any parent driving their kid to school is not? After all, the No. 1 way kids die is as car passengers. Why isn’t THAT endangerment? Why is a good parent only one “who is constantly, obsessively focusing on risk, and not just any risk, but the wrong risk?”

The difference, she eventually realizes, is this: Driving is considered a “must.” You must get the kids someplace, so you do. But letting your child wait in the car, or even play outside on their own, is a decision: You choose to take your eyes off them and do something else for a little while.

Bad mommy.

Choosing convenience and even trusting your kid in the world is the opposite of the intensive parenting norm Kim had been buying into — a norm that now expects parents to wait with their kids at the bus stop, arrange their playdates, solve their spats, call their teachers and eat soggy pizza at all their friends’ birthday parties. And while this demanding regime is not officially “anti-women” — heavens, no! — it just happens to allow folks to shame and even arrest moms (and sometimes, yes, dads) for making life-easing decisions that allow them a modicum of freedom.

“I began to see it for what it was,” Kim writes of the helicopter parenting mandate, “a socially contagious stream of general anxiety that attached itself to one threat, then another, then a different one after that, morphing and evolving but ultimately inextinguishable.”

On the advice of her lawyer, Kim eventually pleaded guilty and got 100 hours of community service for leaving her kid in the car. But her real community service is this book, revealing the persecution of normal, busy parents for what it is: fake safety with real-life repercussions for how we are allowed to raise our kids.

The truth is you can love your kids, care about their safety and take your eyes off them sometimes. That is not a crime. It does not deserve punishment.

Lenore Skenazy is president of Let Grow, a nonpartisan group promoting childhood independence and resilience, and the founder of Free-Range Kids.