Spoilers are precisely defined here. Rules vary by the story's medium. Info from television stories can't be added here until after the top or bottom of the hour, British time, closest to the end credits roll on BBC One. Therefore, fans in the Americas who are sensitive to spoilers should avoid Tardis on Sundays until they've seen the episode.
Shub-Niggurath was an outer god created by H. P. Lovecraft. Worshipped on Earth and Yuggoth, her cult is apparently connected with fecundity, which would make her grandchildren, the Autons, her "thousand young".