The movie version of the pregnancy how-to book is a confusing, shallow* ensemble piece with big stars about five women at different stages of pregnancy and their partners.

“What to Expect When You’re Expecting” is essentially the Hallmark card version of the very specific how-to best seller by Heidi Murkoff.

As Murkoff knew and mined so well, there is a lot of nature-made comedy to be found in the discomforts* of distended* bodies, raging* hormones* and altered relationships. There is also pain, especially for couples who cannot conceive*.

The movie, directed by Kirk Jones, has grand ambitions* and has signed on a cast of thousands to try to touch all those bases.

But rather than the engaging enlightenment* of the source, the film becomes bloated* by confusion. It opens by parachuting* into the lives of five couples in various states of impending* parenthood, then drops in on a “Dudes Group” of four already-entrenched dads and a cool guy who keeps turning up to remind the fathers of what they are missing.

Running around the edges are countless tykes*, none of whom are even slightly memorable despite their extreme cuteness.

A considerable amount of star power is expended on spinning out the complex coupling stories. There are Cameron Diaz and Matthew Morrison, a television fitness guru* and a dancer, respectively, who meet on a “Dancing With the Stars”-type show and end up with a bun in the oven.

Then there is Elizabeth Banks as a militant mommy wannabe* who runs a bookstore. She and Ben Falcone are struggling to conceive. Playing Falcone’s moneybags father is Dennis Quaid and he has a trophy* wife in Brooklyn Decker, who winds up pregnant with twins.

If that is not enough to keep track of, Jennifer Lopez plays a photographer, and she is hoping to adopt a child from Africa with her partner, the handsome Rodrigo Santoro. Meanwhile, Anna Kendrick and Chace Crawford are former high school flames, now food-truck competitors, suddenly dealing with a one-night stand shocker.

As a filmmaker, Jones seems to favor what-makes-people-tick tales — his best was his first, 1998’s “Waking Ned Devine.” “What to Expect When You’re Expecting” has moments that reach the emotional resonance* and clever irony of “Waking Ned Devine” about greed and the untimely* death of a lottery winner. But more often, the ensemble comedy with its many entanglements* flow badly. (SD-Agencies)