Kirk Jones' patchy comedy about the terrors and joys of conception, pregnancy and childbirth has an ensemble cast that includes Cameron Diaz and Jennifer Lopez.

Film: What to Expect When You're Expecting

Director: Kirk Jones

Cast: Cameron Diaz, Jennifer Lopez, Dennis Quaid, Chris Rock

I'm not sure where the market for this film is, though: those who don't have children would find it rather agonising, while those who do might not wish to pay a babysitter for the pleasure of seeing a film about nappies and epidurals.

I grew weary of the way it kept insisting on turning pregnancy into the very broadest of slapstick, a condition which apparently involves leaking one bodily fluid or another in any number of hilariously embarrassing situations.

Early on, as a newly pregnant fitness guru Jules (Cameron Diaz) is reaching the frenzied finale of her reality show dance routine, I wrote dully in my notebook: "She is going to vomit on stage."

Sure enough, a few minutes later, there the offending substance was, swilling around in the dance champions' cup. There are amusing moments, mainly from Elizabeth Banks as owner of a twee pregnancy boutique, who finds the "glow" of her own difficult pregnancy somewhere between ashen and sickly green; and a scene in which a bunch of buggy-pushing dads are filmed in slomo to a heavy rap soundtrack was fresh enough to be genuinely funny.

Yet in the main I knew exactly what to expect when this bunch were expecting: from breaking waters to hormonally inspired weeping, very little came as a surprise.