Charlize Theron's new dramedy is so realistic about parenthood you might wince between the laughs.

There’s s sense throughout “Tully” that another shoe will drop, must drop, to justify the story.

Charlize Theron plays a frazzled mom whose life regains some normalcy after a night nurse enters her life. The dialogue crackles, the obstacles are all too real and laughter bubbles up from what all parents know.

The gig is hard. Brutal.

So what’s the point? Just wait. Director Jason Reitman (“Juno,” “Young Adult”) has something to say above and beyond the lessons learned by moms throughout the ages.

Theron stars as Marlo, the mother of two young children with one more on the way. That’s a blessing on many levels, but Marlo recognizes what else it means. More diapers. Much less sleep.

So when her jerk of a brother (Mark Duplass) offers to hire a night nurse for her you’d think Marlo would pounce on the offer.

Not quite.

She doesn’t want some stranger bonding with her new baby. In the immortal words of every action pic hero, “I got this.”

She does, until she realizes she really could use some sleep after the baby’s arrival. When Marlo finally relents she’s shocked at how much better her life becomes and how quickly the night nurse becomes part of her world.

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Movies have been cracking wise about motherhood for decades. You know the drill: the wacky diaper changing montage. The baby burp that leads to a horrible stain (or more). The wailing kid who won’t let you get back to sleep.

Yuk yuk.

“Tully” digs deeper. So much so that new parents might cringe, recognizing all those raw, real emotions right there on the screen. Screenwriter Diablo Cody has been there, ladies. The mother of three clearly took notes.

Reitman and Cody refuse to go for the cheap laughs in “Tully.” The director would rather show a lovingly made bag of breast milk flop open, its contents pouring out to momma’s horror. That’s the reality of being a new parent.

Buckle in.

FAST FACT: Diablo Cody wrote her breakthrough 2007 screenplay for “Juno” from the cozy confines of her local Starbucks.

“Tully” doesn’t leave the fathers out completely. Dads can relate, too, unless they were checked out for those first intense months of parenthood.

Marlow’s husband (Ron Livingston) is a very Average Joe who unwinds at night by blasting strangers to bits on his favorite via video games. Life hack for the gents. That’s rarely a turn on for your Missus … and it matters.

Mackenzie Davis plays Tully, a 20-something who feels both familiar and new. She’s an old soul packed in a skinny, youthful package. Somehow she senses what Marlo needs at any given moment, but she’s also a person who think personal boundaries are for other people.

She’s comforting and kind, ready with an arcane fact to disrupt any awkward moments. What could go wrong?

Screenwriter Diablo Cody has been there, ladies. The mother of three clearly took notes.

Meanwhile, Marlo must do her best to parent their young son, Jonah (Asher Miles Fallica). He’s “quirky,” we’re told over and again.

“Do I have a kid or a ukulele?” she barks to a school administrator. Jonah appears to have sensitivity issues, along with chronic behaviors that would drive any parent to distraction. His condition makes day to day parenting tougher, as if it weren’t hard enough already.

Theron is, yawn, spectacular once again here. It’s her scenes with Tully that reveal her character and what mothers face in western culture. Those moments are the roadmap to “Tully,” the reason the story exists in the first place.

That said, Livingston should have had another scene or two here. He’s not a cipher, but we’d like to see more connection between the two, or get his sense of the impending drama of a new child. Children are, indeed, a blessing. They also place a strain on even the best relationships.

Marlo and Tully inevitably bond, but what’s next? Will romance blossom, given a brief early scene involving Marlo’s ex girlfriend? Does Tully has a sinister edge?

Stay tuned. “Tully” has the answers, and it’s a rich, rewarding journey to find them out.

HiT or Miss: Had “Tully” simply been a fresh take on the “how hard it is to be a mommy” template it would merit a recommendation. The film provides so much more, including laughs that may leave a mark on parents in the crowd.