What to Expect When You’re Expecting is the latest comedy to be based on a self-help bestseller. What’s next, Jennifer Aniston and Ashton Kutcher in The Seven Habits of Highly Effective People?

Adapted from Heidi Murkoff’s 1984 pregnancy bible, What to Expect takes six lightly- sketched couples and weaves them into the impending-motherhood equivalent of one of those synthetic ensemble romantic comedies.

As sociology, the movie is skin-deep. But if you’re a parent or preparing to be one, you’ll probably see yourself in at least a few of these characters and have a good time doing so.

Elizabeth Banks is terrific as a baby-book author having her first child, a woman in the full dramatic throes of the bodily-function awkwardness of pregnancy. Ben Falcone, from Bridesmaids, is equally as good as her doting, milquetoast husband, but Dennis Quaid, as Falcone’s ex-racing-star father (who is having twins with his trophy wife), is playing an alpha-male cartoon.

Cameron Diaz (as a diet-reality-show host) and Matthew Morrison, as the father of her child, spar painfully well as a couple who can’t agree if the son they’re about to have should be circumsized. Jennifer Lopez and Rodrigo Santoro are touching as a couple out to adopt.

There’s also a very funny pack of defeated young dads who carry themselves like the living dead. As the father of an 18-month-old myself, I have to admit I could relate to everything they said.

Last and least, Anna Kendrick and Chace Crawford act out an unconvincing, bite-sized Knocked Up.

What to Expect When You’re Expecting is sort of thrown together, but that’s okay: It hits authentic notes of anxiety and joy.