Most everyone has some memory or another of 1943, the top-down airplane bullet-hell shooter to which we all lost a good deal of quarters.
When I think of 1943, I think of things like "Difficulty" and "Insane Difficulty." I do not, however, think of a flying baby. But in the Japanese ad campaign for the game, someone decided that a flying baby would be just the thing to sell viewers on it.
Maybe it conveys a sense of… fun? The baby does look like it's having fun...