According to the Hiroshima Prefecture Guidebook, “commoners, the elderly and women are no longer banned,” though, “visitors to Miyajima island are asked to respect the following simple rules:
1 No cutting down trees;
2 No giving birth;
3 No dying.”

Crossing on the ferry, I wondered how these regulations might be applied. But, everyone knows society’s rules so if you might fit any of the criteria and you’re Japanese, you don’t go to Miyajima.