Don’t expect much from this latest example of a troubling cinematic trend—the effort to construct an ensemble comedy from the shards of a best-selling advice book. Following in the footsteps of “Think Like A Man,” jerry-built from Steve Harvey’s tome, comes “What To Expect When You’re Expecting,” which takes its title, at least, from Heidi Murkoff’s 1984 self-help manual. What screenwriters Shauna Cross and Heather Hatch, director Kirk Jones and a starry cast have managed to deliver is an episodic extended sitcom that offers a mountain of bad jokes unrelieved by the occasional burst of mawkish sentiment. You might think it was Garry Marshall’s latest holiday-themed multi-subplot stinker.

A surfeit of characters are caught up in this muddle. First, of course, are the expectant couples. Jules (Cameron Diaz), host of a TV fitness show, is pregnant by Evan (Matthew Morrison), who also happens to her partner on a “Dancing With the Stars”-style reality series. (They win, but she throws up into the trophy on air—the first of many such ultra-sophisticated moments.) Wendy (Elizabeth Banks), who’s apparently some sort of activist for breast-feeding, is happily with child after years of trying with dumpy hubby Gary (Ben Falcone). Never to be outdone by his son, Gary’s ex-NASCAR driver dad Ramsey (Dennis Quaid) announces that he and buxom trophy wife Skyler (Brooklyn Decker, going for exaggeration to balance her bland turn in this week’s “Battleship”) are also expecting—except that they’re going to have twins. Then there’s perky Rosie (Anna Kendrick), a food-truck worker who’s knocked up in a one-night stand with Marco (Chace Crawford), an old schoolmate who’s now her counterpart on a rival truck. On a separate track is Holly (Jennifer Lopez), a photographer who can’t have kids and, along with hubby Alex (Rodrigo Santoro) is looking to adopt.

It will come as no surprise that most of the couples, after a various of slapstick episodes, wind up in the hospital at precisely the same time, and just as Holly and Alex make their way to Ethiopia for an adoption ceremony. One doesn’t: the pregnancy comes to an unfortunate end. (This is the sort of shameless picture that turns a miscarriage into a maudlin musical montage.) But even this isn’t enough for the filmmakers. They add a sort of chorus of dads who gather to walk their kids in the park and babble on about the joys and burdens of parenthood like a bunch of stand-up comics, with Chris Rock loudly leading the pack (which also includes Matthew Morrison, Thomas Lennon and Amir Talai). And of course the whole thing winds up in an orgy of ultra-cute bits with babies played through the final credits.

“What to Expect” runs slightly under two hours, but it feels like the full nine months. There’s not a genuine instant in it: every dialogue scene is forced, with synthetic speeches and one-liners cascading out of characters’ mouths and the situations coming across as totally artificial, the serious and cloying moments even more than the broad, comic ones. Most of the lead cast appear so fleetingly that they can’t do much more than recite the lines (Falcone is drab even doing that), but some—Diaz, Banks and Decker among the women and Quaid among the men—overplay so hugely that they turn into caricatures. A special category is reserved for Rebel Wilson as Wendy’s bulbous, sweetly dim assistant Janice. With her slightly stoned demeanor she seems intended as weird comedy relief in a movie that already has too much bad comedy but needs to give us some relief.

“What to Expect” is technically proficient, with Xavier Grobet’s cinematography clean and bright, and you have to feel for editor Michael Barenbaum, tasked with the need to stuff all the plot strains into a decently unified whole. The crew give the material more professionalism than it deserves.

It all makes you wonder whether the brains behind “What to Expect When You’re Expecting” followed a second advice book in making it—“Moviemaking for Dummies.”