Okay, as I write this review for “Tully,” the latest collaboration between filmmaker Jason Reitman and writer Diablo Cody, I have to confess I am not a parent. I have not experienced restless nights with a crying newborn who constantly needs a bottle of milk or a quick diaper change, and if I ever do become a parent, I am certain I will deal with it as well as my friends with kids have (which is to say, not at all). But after watching “Tully,” I feel confident in saying it is one of the more honest depictions of what a mother goes through before, during and after she gives birth. Whereas most movies conclude with the birth of a child, this one starts with one and goes from there.

Charlize Theron plays Marlo, a mother of two and with a third on the way. Her belly is so big to where she looks ready to burst at any second, and we also see how overwhelmed she is with everything and anything. Her son Jonah (Asher Miles Fallica) is an overly-sensitive boy who freaks out loud noises he is exposed to, and she is forced to give him more attention at the expense of her daughter Mia (Lia Frankland). When Marlo visits the principal at Jonah’s school and tells her this third child is “such a blessing,” you can tell she doesn’t fully believe it.

When Marlo does give birth to a girl she names Mia, it is one of the more unique birth scenes in movies. Most filmmakers treat the arrival of a newborn with unfettered joy, but “Tully” treats it dispassionately as Marlo is too wiped out and depressed to be happy about anything. For a moment, I feared this movie would venture into “We Need to Talk about Kevin” territory, but neither Reitman or Cody are out to make this story about a sociopathic child.

From there, Reitman presents us with a furious montage of Marlo constantly getting up in the middle of the night to take care of her crying baby, feed her, change her diapers (always an unappealing task), and pump milk out of her breasts. Sure, Marlo does have a loving husband in Drew (Ron Livingston), but he has yet to fully see the heavy toll motherhood is taking on her. It’s an unnerving montage as we keep waiting for Marlo to explode in frustration, and when she eventually does, you cannot blame her.

Marlo’s brother, Craig (Mark Duplass), comes to her rescue by offering to hire a night nanny. Marlo is at first very hesitant to let Craig do this as the thought of anyone else raising her children is terrifying, but one day after she is unable to stop Mia’s crying, she relents. The night nanny comes in the form of Tully (Mackenzie Davis), a youthful woman who quickly proves to be wise beyond her years. Once she comes into Marlo’s life, things begin to change for the better, but as the movie goes on, you wonder more about who Tully is and if she is too good to be true.

Watching “Tully” reminded me of many scenes in movies and television where I witnessed a mother losing her patience. We watched Marge Simpson roar like a lion at anyone who couldn’t possibly understand her frustrations, we were taken aback when Dee Wallace yelled at her son “alright I’ll get your daddy!” while being stalked by a rabid St. Bernard in “Cujo,” and we watched helplessly as Brie Larson tried to explain to her son what is really going with them in “Room.” Mothers will often explode in frustration, and many of the best movies about parenting portray this. As we see Marlo get upset with her kids, it is highly likely we will be reminded of the agony we put our own mothers through to where a long overdue apology may be required from us. “Tully” has several moments like these, and they are fully earned throughout.

Theron has long since proven to us what a phenomenal actress she can be. As Marlo, she gives a fully realized performance as a mother who looks like the joy she has for life has been completely sucked out of her. The Oscar-winning actress makes you feel the pain of Marlo’s situation as the character has long since reached her breaking point to where she seems like she cannot take another challenge thrown in her general direction. As the movie goes on, we see Marlo rise out of her depressed state to where she experiences happiness for what seems like the first time in ages. Theron makes us feel every note of Marlo’s anguishes and triumphs to where we cannot come out of this motion picture saying we were not the least bit moved.

As the night nanny, Mackenzie Davis proves to be such a luminous presence as Tully to where we realize this movie doesn’t just need her, it deserves her. A modern-day Mary Poppins, Tully predicts Marlo’s every move and need and gives her just what she needs to make it to the next stage in her life. Davis is best known for her work on “Halt and Catch Fire” and for appearing in one of my favorite movies of 2017, “Blade Runner 2049.” She gives off such a warm glow in “Tully” to where you just want to hug here and never let her go.

I also have to give credit to Ron Livingston who plays Marlo’s husband, Drew. It could have been a thankless role of a husband and father completely ignorant of his wife’s suffering, but the “Office Space” actor makes him more than the average movie dad. Even as Drew loses himself in video games which have him battling and killing zombies, Livingston makes us see he is a man with a good heart even with all his flaws. In his penultimate scene, Livingston doesn’t make Drew into a total schmuck who berates his wife when things go haywire, but instead into a spouse eager to admit he doesn’t know everything his wife is going through and is desperate to hear her out. I love it when Livingston says “I love us” instead of “I love you” as it shows the perspective and honesty Reitman and Cody are committed to giving this particular parental adventure, and it makes this moment between these two characters all the more special.

If I have any problems with “Tully,” they come in the second half when revelations are made to where we have no choice but to question everything we just saw I would tell you which movies these revelations reminded me of, but this would be giving away way too much. But while these revelations could have wrecked any other motion picture, they do little to take away from this one.

“Tully” marks a big comeback for Reitman and Cody after a few years of cinematic misfires. “Labor Day” and “Men, Women & Children” put a few dents in Reitman’s resume as a director, and Cody’s directorial debut “Paradise” and screenplay for “Ricki and the Flash” (0ne of Jonathan Demme’s last films before his death) were ill-received to put it mildly. But when these two artists come together, they create something which is never easily forgotten.

Reitman makes the struggles these parents go through all the more vivid without making them seem the least bit glamorous. “Tully” does not have the look of a motion picture to where you feel like you are watching one, but instead of a real life setting with all its messiness and imperfections on display. At times, I felt like I was watching a home movie, and this made everything I saw feel all the more powerful.

As a writer, Cody still comes up with some classic zingers like “abandoned trash barge” or describing someone as a “book of fun facts for unpopular fourth graders,” but her screenplay also shows her rising to another level of thoughtfulness and maturity. Being the mother of three children herself, Cody clearly understands the journey such a person ends takes to where the mother/newborn connection is not forged right away. There has been some controversy over “Tully’s” portrayal of mental illness, and it is never made clear if Marlo is suffering from post-partum depression or something similar. Cody, however, is not out to make Marlo a special case study, but instead to share the challenges she was forced to overcome to be the mom she is today.

I think it is more than appropriate that “Tully” has arrived in theaters just in time for Mother’s Day. Lord knows we owe our mothers a great deal of gratitude for all they have done for us, let alone all they have gone through to get us to where we are today. Sure, dads deserve a lot of credit too, but being a mother comes with a lot more challenges and obstacles to overcome. If this Reitman/Cody film cannot make you see this, then what will?

* * * ½ out of * * * *