Of the sympathetic signs of pregnancy, no one is more common than morning sickness; and when the vomiting becomes obstinate or uncontrollable, no condition connected with the pregnant state is more depressing and exhausting to the vital powers. Mention of this condition is found in the writings of the ancients. Thus, Hippocrates prescribes rules respecting the remedial use of agents for this state; he says: "if matters be turgid [in a state of orgasm] in the pregnant woman, she should be purged"; but adds that purging is unsafe in the earlier and later stages of pregnancy. By purging, Hippocrates does not mean simply the administration of purgatives, for he speaks of purging upward in the summer and downward in the winter. This was done according to the ancient ideas to relieve the contents of the vessels that were ready to burst forth with plethora.
Wilson Fox (Reynolds' System of Medicine,