People on the clock for serious life moves tend to find very little humor in moments of limbo between propriety and uncertainty, expectations and emotions.

Judd Apatow’s movie mission seems to be offering them that necessary comic catharsis, stuff so lean-forward-and-clap funny it must be working on a level stronger than onscreen outrageousness.

Apatow hit a knockout, and a nerve, with 2005’s The 40-Year-Old Virgin. Again, identifiable neuroses, fears and concerns somehow naturally complement all the stoner jokes, pop-culture references and verbal Olympics of profane insults in his latest, Knocked Up.

It’s the story of a California couple in a courtship as unexpected as a pregnancy from their one-night stand, and many of its meaty, hearty laughs generate from organic setups. Plus, it signifies the welcome arrival of Virgin supporting player Seth Rogen as the Tom Hanks of schlubdom.

His Ben is an unemployed, pot-smoking cynic scraping by on vestiges of a personal-injury check and glacially building a celebrity-nudity Web site with a quartet of equally unmotivated pals. Apart from alcohol, what motivates a pretty woman to sleep with him is the hope of all genuinely nice, semi-schmoe guys — that their disarming charm actually will work.

It does, hilariously, in a club, when Ben meets Alison (Katherine Heigl). He’s there to drink and wax philosophical about how Munich boosted the sexual prospects of Jewish males everywhere. She’s celebrating a pending promotion at E! that would spring her from the guest room of sister Debbie (Leslie Mann) and brother-in-law Pete (Paul Rudd, one of today’s smartest comic wingmen).

Their night of unlikely sex leads to a morning-after breakfast where Ben’s dead-end existence comes nightmarishly into view. Alison puts it behind her as a mistake until she nearly throws up on the shoes of James Franco (one of many celebrities in hilarious cameos) during a taping.

Sure enough, she’s pregnant — a result of heated-moment misinterpretation — and breaks the news to Ben. After reconsidering his amusingly rude response, Ben offers whatever support he can. Naturally, they’re beset by opinions on both sides, and the abortion discussion arises, but never becomes an issue to cloud the comedy.

Ben gets both support and disdain from his pals (Jay Baruchel, Jonah Hill, Jason Segel and Martin Starr), while harried Debbie is leery of Ben as a possible parent. Pete feels differently once Ben becomes a buddy with whom he can escape from his demanding daughters. In writing Pete and Debbie’s own woes, Apatow doesn’t deign to suggest blanket answers for relationship problems.

He reserves his old-fashioned heart for Ben and Alison. By default, they date, but neither pretends that romance, or even their togetherness, is contingent for their baby’s life. Rogen and Heigl convey the fragility of the life they’re making in honest, conversational core-cutting dialogue.

All this makes Knocked Up sound like something guys should take for the team. Far from it.

It’s interwoven with crudely riotous jabs at Meg Ryan’s personal grooming, awkward or inept obstetricians, perils of pregnant sex and Debbie’s simultaneously lewd and respectful dismissal by a club doorman (Craig Robinson of NBC’s The Office). If Knocked Up’s length has a plus, it’s that Harold Ramis, Charlyne Yi, Kristen Wiig and Alan Tudyk can make the most of their appearances.

As for that last trimester, it’s too long for the movie to be the second coming of comedy, as Knocked Up’s bizarrely big hype has made it to be.

At an unwieldy 132 minutes, the movie eventually turns into what you expect when someone’s expecting onscreen — albeit with graphic glimpses of the … umm … miracle of birth. What’s more concerning — more scenes like that on an unrated DVD or its possible 150-minute run-time?

Though not quite as polished as Virgin, Knocked Up still is the year’s funniest, and most sincere, comedy so far.