Here's what to expect from "What to Expect When You're Expecting": forced farcical humor, ineptly executed dramatic twists, chemistry-free romantic pairings and absolutely zero resemblance to reality.

There's nothing to say that turning Heidi Murkoff's enduringly popular — if frequently criticized — nonfiction pregnancy guide into light escapist entertainment is fundamentally misguided, but "What to Expect" doesn't offer much evidence that it's a particularly good idea either.

Very much in the mold of insipid hits "He's Just Not That Into You" and "Valentine's Day," "Expecting" assumes that cramming a bunch of famous (or almost famous) faces into a hodgepodge of loosely connected vignettes is enough to make a movie. Of course it's not, but these concoctions usually make enough money to justify the laziness of their creators. Even the superior recent "Think Like a Man" (the "Philadelphia Story" of airheaded we've-got-a-title-now-we-need-a-plot! ensemble rom-coms) was a surprise box office hit. At least Garry Marshall's "Valentine's Day" follow-up "New Year's Eve" was a commercial disappointment. With any luck "Expecting" will follow suit.

The wisp of a plot charts the interlocking stories of five couples facing impending parenthood: reality TV star Jules (Cameron Diaz) and her on-camera dance partner Evan (Matthew Morrison) learn they'll have to put egos aside to get ready to raise a baby, photographer Holly (Jennifer Lopez) and her jingle-writing husband Alex (Rodrigo Santoro) are applying to adopt an African newborn, uptight Wendy (Elizabeth Banks) and her husband Gary (Ben Falcone) have been struggling for years to get pregnant and finally manage it at the same time Gary's father (Dennis Quaid) discovers his much younger new wife (Brooklyn Decker) is also expecting, and rival food truck operators Rosie (Anna Kendrick) and Marco (Chace Crawford) are thrown for a loop when their one night stand results in a bun in the oven. Meanwhile, Alex keeps running off to a local park to get advice from experienced dad Vic (Chris Rock) and his friends Gabe (Rob Huebel), Craig (Tom Lennon) and Patel (Amir Talai), who serve as a sort of Greek Chorus of reality checks for fathers-to-be.

The already overcrowded cast also includes "Bridesmaids" co-stars Wendi McLendon-Covey as Holly's boss and Rebel Wilson as Wendy's employee, and "True Blood" co-star Joe Manganiello as a single playboy who Vic and pals live vicariously through. Perhaps it's simply a case of biting off more than you can chew, but screenwriters Shauna Cross ("Whip It") and Heather Hach ("Freaky Friday") fail to give any of the individual stories enough weight to emotionally invest in or enough effervescence to make them enjoyable to watch. Everything is pitched at the same superficial sit-com level: from Jules and Evan arguing over whether or not their child will be circumcised to Wendy's discomfort with her changing body to Holly and Alex prepping for an interview with an adoption agent (Kim Fields, updating her entry for the next "Facts of Life" stars: Where are they now? story). You probably can (or maybe even have) seen all these storylines played out with a laugh track on CBS.

Beyond a few of Rock's Bill Cosby-lite rants about fatherhood (which are no match for the sort of sharp observations he's known for as a stand up) and one mega-meltdown from Banks, there's very little in the movie that actually even lives up to the title. If the point is to suggest that the experience of being pregnant is exactly like you've seen in every other stupid Hollywood comedy from "Nine Months" to "Father of the Bride Part II," then it's a success.

There are some likeable elements in play here: the cast is generally solid — no one embarrasses themselves as badly as the stars in "Valentine's Day" — and Elizabeth Banks and Anna Kendrick are even better than solid despite roles that are utterly clichéd and woefully underwritten respectively. Unfortunately, the ADHD ensemble format does no one any favors, especially in the overly saccharine hands of director Kirk Jones ("Waking Ned Devine," "Everybody's Fine"). By jumping from story to story without ever developing a rooting interest in any of the characters, the film quickly devolves into a hyperactive mess of endless punchlines and no soul.

When Rosie and Marco's story takes a serious turn, it's like a slap in the face. Not because Kendrick can't handle heavier material, but because the movie she's in can't handle anything more challenging than spot-on but toothless parodies of "Dancing with the Stars" and "The Biggest Loser."

But let's be honest. You've either assumed all of this already when you saw the trailer or you don't care about any of these things and just want to see the movie because you think it looks like a laugh riot.

So here's an easy way to figure out if the movie is worth your time: Is the sight of a woman in labor screaming for drugs ever not hilarious? If you can honestly answer yes, then you might want to see "What to Expect When You're Expecting" after all. Just leave everyone else out of it.

"What to Expect When You're Expecting" opens nationwide May 18