Judd Apatow’s “This Is 40” is Ron Howard’s “Parenthood” with raunchier language and situations. Both are about an upscale married couple dealing with the problems of parenting, failing businesses, and dependent parents.

Where Howard had Steve Martin and Mary Steenburgen, Apatow has Paul Rudd and Leslie Mann. Where Howard had Jason Robards as the cranky father, Apatow has Albert Brooks.  Where Howard had cute kid actors, Apatow has his own daughters (with built-in comedic chemistry). Where Howard’s supporting cast included Dianne Wiest, Rick Moranis, Martha Plimpton, and Tom Hulce, Apatow has Megan Fox, John Lithgow, Robert Smigel, and Jason Segel. Both movies have some good performances and funny scenes, but in the end, not much cohesion. They don’t have a plot as much as they do sketches stitched together around a theme.

What they also have in common — spoiler alert! — is a plot twist involving the wife, who is surprised to find herself pregnant years after what (she thought was her) last child was born but, like the couple in “Parenthood,” Apatow’s Pete and Debbie (Rudd and Mann) don’t even pause for a discussion of whether they should keep the child. I know that abortion is a dicey topic for a comedy, but if Amy Heckerling worked it into “Fast Times At Ridgemont High” 30 years ago without creating controversy or bringing the story to a screeching halt, there’s no reason Apatow can’t have his characters at least talk about the choice, including the financial burden another child will place on their already fragile fiscal condition.

But responsibility when it comes to finances isn’t a factor in this couple’s decision-making. Despite his failing independent record label losing money hand over fist, and her boutique’s employee theft problem, Pete and Debbie still take time to spend a weekend away at a fancy resort, and then return to throw a big backyard birthday party (they’re both turning 40 at the same time), complete with a tent, a caterer, and dozens of guests. There’s no effort made to explain how they can afford this, just as the topic is avoided when it comes to the impending new addition to their family.

Wacky comedies don’t have to stick to normal everyday logic, but they do have to hew to their own internal logic, and “This Is 40” doesn’t do that. It didn’t have to get bogged down in ponderous discussions of these matters, but it shouldn’t have skated completely around them, either. Perhaps Apatow should have studied Brooks’ classic “Lost In America” for ideas on how to make Pete and Debbie deal with their money problems while still being hysterically funny.

One thing that “This Is 40” does very well is provide a showcase for Mann, who happens to be Apatow’s wife, in her first real starring role. She’s a good comedienne, very attractive, and not shy about showing off her body — although I wonder what the negotiations between actress and director regarding her topless scenes in the movie were like at home.

I’d bet that Leslie and Judd talked about the matter a lot more than Debbie and Pete would.