I've seen the future. And it burps

Rugrats are the cartoon babies who grew and grew. Now they're poised to take over the world. You have been warned

Amelia is disappointed. It is Thanksgiving weekend and she's just been to see The Rugrats Movie, the film of the television cartoon series about talking babies, with her father and sister.

"I thought it was going to be set in ancient Egypt," she complains.

"That's Prince of Egypt, dummy," her sister Martha retorts. "That one hasn't even come out yet."

A couple of queues away outside the multiplex, Jason and his dad Mike said they had been planning to go and see Rugrats themselves until they realised that Babe: Pig in the City (the much-anticipated follow-up to the runaway farmyard smash of a couple of years ago) was opening on time, despite much-trumpeted reports of delays and last-minute editing changes.

Not that those two were the only choices on offer. In the squishy department there is A Bug's Life, Disney's pixel-animated follow-up to Toy Story, not to mention DreamWorks' slightly earlier release on much the same subject, Antz. For parents wishing to instill a bit of film culture into their offspring, The Wizard of Oz has obligingly just returned to the big screen in a holiday season re-release. Prince of Egypt, an animated version of the Moses story, will hit cinemas early next month. And Christmas is slated to bring yet more goodies for younger audiences.

It's a confusing, crowded world out there, with the Hollywood studios laying out a tantalising array of wares for children and competing furiously for their custom. Or rather, competing for their and their parents' custom. It's no longer enough to have linear plotlines, or straightforward cuteness, or an extended Tom and Jerry-style chase sustaining 90-odd minutes of entertainment. No, to draw in the all-important parents, children's films these days need complex characters, in-jokes, knowing references to movies, books and television programmes and, preferably, a whiff of sexual innuendo as long as this can be slipped in innocently enough. All of which might explain why The Rugrats Movie has snuck up from behind on its big-gun rivals and become the early smash hit of the season. The film barely got reviewed, and when it did, critics provided little more than a polite plot summary. Variety, the industry bible, forecast a discreet theatrical run, with the real market to follow in video. But, to everyone's surprise, audiences began snaking around the block, and the film cashed in an extraordinary $27.3m on its opening weekend. Not bad for a cartoon about a bunch of babies.

What the film critics did not realise, but what every American parent knows all too well, is that Rugrats has become quietly ubiquitous over the past couple of years. Not only is it the number one cartoon show on US television, but it has branched out into merchandising in a big way. Phil and Lil, the one-year-old DeVille twins, turn up on toddler-sized juice boxes in supermarkets. Advertising supplements promoted by the big children's stores feature Rugrats quizzes and Rugrats wristwatches.

There may not be an enormous amount of psychological complexity to the likes of Tommy Pickles, his neurotic friend Chucky and the spiteful four- year-old villain of the piece, Angelica. But it is enough to keep the kids watching from frenetic vignette to frenetic vignette, and to pique adult interest too, at least for a few minutes at a time. Rugrats is a Charlie Brown for the video age, a portrait of engagingly dysfunctional youth (in this case extreme youth) that has been edited like an MTV video.

Indeed, Rugrats has been described as ideal viewing for short attention spans. The characters, the humour and the knowing references are all there, but such complexities probably elude most first-time viewers. Adults have a tendency to get bored and wander off after a few minutes, while the children remain glued. The hidden delights of the show are something that parents tend to absorb, almost by osmosis rather than through any real concentration, over an extended period of time.

That, in turn, explains why it took a good four or five years for the show to take off on US television, and why it has yet to make much impact in Britain, despite kicking around for a good while. Created by the former husband-and-wife animation team of Arlene Klasky and Gabor Csupo, who also helped conceive The Simpsons, Rugrats was actually pulled off the air after its first couple of seasons. It was only when the show was syndicated and subjected to endless reruns that it really hit its stride.

The Rugrats are not cute, or loveable, or schmaltzy in any way. Rather, they derive their charm by portraying infants in all their infuriating diversity. Tommy, Chucky, Phil and Lil and the others have the sort of heads that look as though somebody dropped them. They have either next to no hair or, in Chucky's case, an over-abundance of shocking red. They scratch their bottoms, wiggle their nappies, throw up, fart and wail just like toddlers anywhere. They pull each other's hair, throw food, fight over toys and lose no opportunity to whack each other around the head.

The premise of the show, though, is that they also talk (much like adults, although seeing the world from a child's point of view) as soon as their parents are out of earshot. Not only that, but they prove themselves to be no less immature in their own way as their disappointing parents. Their evident savvy adds extra poignancy to their relationship with the troublesome Angelica, who is forever creating trouble for them, for her workaholic parents and for herself. Her pet phrase, and indeed the signature phrase of the whole show, is a derisive "You dumb babies!"

To the extent that the show has generated any controversy, it has focused on Angelica. The creators say they felt they needed a bully figure, since dealing with bullies is what childhood is all about.

But debate has simmered over the years, both within the creative team and the public at large, whether Angelica's meanness is really appropriate for an audience scarcely any older than the animated characters. Early on in the series, she ran away from home, attempted to pin blame for outrageous acts on her cousin Tommy and his friends, and sued her parents for forcing her to eat broccoli.

These might seem like reasonable plotlines for a children's cartoon, but in the US the offspring of the baby boomer generation has been subject to unprecedented scrutiny and psychobabble when it comes to appropriate behaviour, language and role models. Rugrats has attempted to tread the same fine line being drawn up in pre-schools and kindergartens. Should children's behaviour be categorised as good or bad? (No, says the prevailing wisdom.) The Rugrats never do anything domestic irresponsible, like sliding downstairs on the back of a vacuum cleaner, say. Instead, they have a lot of adventures in forests, office buildings and shops. Angelica's dastardly side never escapes punishment and her character has a token ounce of sweetness.

This kind of kid-glove approach to children's programming dates back to the 1960s, when the networks came under pressure to tone down the violence typical of the old Warner Brothers cartoons. Eventually, the number of times a cartoon character could be pounded into the ground was restricted to a couple of instances per episode.

With the flourishing of a hipper brand of children's cartoon in the 1990s, starting with The Simpsons, the attempts to keep the airwaves sweet and reasonable have become more subtle but no less influential. The idea of developing shows like Rugrats was to tap into eccentric animation and writing talent, then try to find a way to keep the excesses and exuberances under control - making the show thrilling and harmless at the same time.

The new movie is a good case in point. The plot of this 80-minute caper revolves around the birth of Tommy's baby brother, Dyl Pickles. Angelica stirs up Tommy's jealousy at the new arrival and causes him and his friends to vow to take Dyl back to the baby shop for a refund. In a series of complicated twists, the whole gang of toddlers winds up with the baby in the middle of a mountain forest. Angelica comes after them in the belief that they have kidnapped her doll, Cynthia, and ends up protecting them from a wolf. Parents and grandparents argue about who is responsible for the missing children and rush along in pursuit.

Again, the plot twists are accompanied by a politically correct message. Parents, don't lose track of what your children are up to. Don't fall asleep like Grandpa Lou, only to find the little ones gone when you wake up. Children, don't do anything foolhardy if you get lost. And so on, in right-on fashion. For this reason, Rugrats comes across as a bit bloodless, a bit too safe, a bit boring. The soundtrack and swift editing keep it noisy and distracting, but what it needs is a dark, slightly perverse side that is unafraid to take child audiences down the same sort of perilous avenues explored in the Grimm fairy tales.

In America it has caught on because it captures a certain spirit of the age in a country where seemingly everyone is having children and then worrying about the world they are being brought up in. No doubt publicity, product placement and savvy marketing might provoke a Rugrat infestation in Britain to coincide with the movie's release. It remains to be seen, though, whether it has the power to speak to a generation of parents and children, or whether it will just come across as another dumb American cartoon show.