I opted to look at six of the most popular and prolific small horror presses (because, frankly, I'm not going to spend more than an hour on this): Bad Moon Books, Bloodletting Press, Cemetery Dance, Chizine, Delirium, and PS Publishing. I noted the total number of books they published in 2010, and how the gender split broke down.
Granted, I probably missed some titles - it's not always easy to figure out what was published by which imprint of the press in which year, etc. etc. Other criteria: If a book was a small collection of different authors (no more than 4 or 5) or a collaboration, I included all the authors, but if the book was an anthology, I only included the editor.
So, basically 7.07% of small press horror books in 2010 were by women.
Okay, I'm sorry, but...that's pathetic.
I hope it means the women are off making way more money writing paranormal romance and urban fantasy for major publishers. But...
I'll bet more female authors would venture into the small press world if it didn't just look like a boys' club from the outside. Are these publishers doing anything to court women writers? Not that I know of. I hear from male writing friends frequently about being invited by these presses, but I don't hear those tales from my female writing pals. My personal experience is that three of the publishers listed above simply never responded to submissions I made. Maybe that was just me. But looking at these numbers...well, draw your own conclusions.