I don't know why anybody takes this seriously. Think about it--does every single human being have bad luck on this day? If so, what is the source of this bad luck? Is there something lurking in the cosmos that dictates good and bad luck? Assuming that this is the case, how does the Cosmic Luck Genie know what calendar date we puny humans assigned in our geographic area of the planet on this day?
I had the same problem with the Y2K scare. The arbitrary assigning of a date by human beings really has no impact on the universe. Different parts of the world use different calendars and our version doesn't take precedence. In fact, our version has been tinkered with a number of times over the centuries.
So, even though there may be more births and crazy stuff going on during a full moon, Friday the 13th ain't gonna hurt yah!