Postpartum taboos on sexual intercourse have been encountered in many countries throughout history. They were once advocated by medical authorities in Europe. The Greek and Roman doctors of antiquity were opposed to sexual relations during nursing and their opinions were quoted until the nineteenth century. Galen (1951:29) thought that the milk of the nursing mother would be spoiled because of the admixture of sperm in the mother's blood. Soranos and Hippocrates believed that coitus and passionate behavior provided the stimulus that reactivated menstruation. Prior to the eighteenth century, there was no medical knowledge of the biological effect of bring on inence, and not the action of breastfeeding, was thought to delay the return of menses. This interpretation was still vivid in Europe in the eighteenth century.