Creepiest Movie Children - Rotten Tomatoes
The Brood (1979)

When he's on his game, nobody does horror like David Cronenberg, and this was a disquieting preview of the horrors he'd inflict with later films (i.e. The Fly, Dead Ringers). This is a nightmarish world where a deranged psychotherapist has developed a technique which allows patients to create physical manifestations of their negative emotions. Or, in the case of one poor woman, pop them out as telepathic murderous mutants. On the bright side, she probably didn't have to spend a lot of money on diapers.