Upvote:2
Cursory googling suggests the superstitions date back to Hindu beliefs and Aztec times, so tracing the superstitions' exact origins and their precise explanations may prove very hard or impossible.
That said, their explanations probably are related to this:
"If you do a worldwide survey of eclipse lore, the theme that constantly appears, with few exceptions, is it's always a disruption of the established order," said E. C. Krupp, director of the Griffith Observatory in Los Angeles, California. That's true of both solar and lunar eclipses.