I personally don't think that God meddles in the minutia of existence by default. As such, I think the question is whether God is cruel because he allows deformed children to be born, not whether God creates deformed children. And I think that deformities and other misfortune are part of the milieu that makes us what we are. The thought experiment of imagining a world that knows for certain that God exists and what He wants or the thought experiment of imagining a perfect world with no misfortune or deformities suggests that these sorts of worlds would not be a preferable alternatives, much in the way that "nobody ever makes a mistake and everybody always wins" would render most competitions, sports, and games unbearably boring and pointless. It is no mistake that it is the bored and affluent like bin Laden, who would normally have few risks or challenges in his life, seek out danger and trouble. And I also think the mistake that many Christians make is that they don't seem to imagine that God could take the hand you are dealt into account when judging how you are doing or how you did.
But my point remains. These children are not "mistakes" in the sense that they are any less valuable or worthy of life than any other child.