The First Sex Manual Published in North America, 1766 (SFW)

Printed in Boston in 1766 (after first being published in England in 1684), it's titled Aristotle’s Complete Master-Piece, In Three Parts; Displaying the Secrets of Nature in the Generation of Man (find a copy online here).

The work—thought to have been written by a self-proclaimed English “Professor of Physik” named William Salmon—has, in fact, nothing to do with Greek philosopher Aristotle; his name provided the text with authority its true author lacked (such pseudepigrapha had been in fashion for ages). It was immensely popular on both sides of the Atlantic. Despite the fact that it may be the least prurient book about sex ever written, it remained the most widely circulated guide to sex and reproduction in North America until 1830.

Pregnancy out of wedlock could produce an infant covered in hair or Siamese twins:

Read more at Open Culture.