Soranus (A.D. 98-138) was a Greek physician who studied in Alexandria and later practised in Rome under Hadrian. He found enough time to write forty books or so. In his "Gynaecology" he suggests"...that a woman ought, in the moment during coitus when the man ejaculates his sperm, to hold her breath, draw her body back a little so that the semen cannot penetrate into the os uteri, then immediately get up and sit down with bent knees, and in this position, provoke sneezes" (quoted by S. Green, "The Curious History".) Thus, it is hoped, she will avoid conception.