There is a very interesting article in the latest issue of Archeology about the old ways in which women controlled their own bodies and reproduction. Apparently all this nonsense about birth control being a miracle of modern medicine is just that. These authors contend that the evidence was always there in the ancient writings, but nobody ever paid much attention to it.
The best and most popular around the 7th century BCE was Silphium, a plant that was so widely used in the Mediterranean area that it made the people of Cyrene (now in Libya) very rich. It became extinct by the 3rd or 4th century CE but not before dramatically reducing the population growth of the Roman empire. The popular myth is that infanticide is responsible for the decrease in population, but archaeological evidence has never borne this out.
The popular substitutes and other resources, some of which have been in continuous use up to this day are: the seeds of Queen Anne's lace (the wild carrot), pennyroyal (often used now days but potentially more toxic than some of the others), artemisia, pomegranate (in the story of Persephone, eating six seeds produced six months of barrenness on the earth), myrrh, and rue. Acacia gum with other substances was used by the Egyptians as a vaginal suppository to induce abortions. It is a modern ingredient in spermicides, by the way.
The authors speculate that the art of effective birth control was lost in the middle ages when medicine became a university topic and the realm of child birth and other reproductive matters became the domain of midwives. The herbalists, midwives and "witches" didn't lose the arts, but the medical profession did to the point of believing that no really effective means of controlling fertility existed.