As Christianity and in particular the institution of the Catholic Church increasingly influenced European society, those who dispensed abortifacient herbs found themselves classified as witches and were often persecuted (see witch-hunt).
Source: Wikipedia
I never knew this, but it makes sense.
What people sometimes fail to realize is that contraception was universally CONDEMNED by all Christians (Catholic, Protestant and Orthodox) prior to the 1930 Anglican Lambeth Conference and that, after the Conference, all major Protestant denominations condemned the new Anglican position.
http://www.freerepublic.com/focus/religion/2613655/posts