"In Japan, Dr. Tenrei Ota, born in 1900, began pioneering intrauterine contraception in the 1930s. Once his country had joined the Axis and contraception was forbidden, Dr Ota became a political target, changed his name and finally went into hiding. As a consequence, knowledge of the Ota Ring would reach the Western world only after the end of World War II. Dr Ota had initiated his experiments in intrauterine contraception by inserting objects made from a great variety of materials and shapes, from gold spheres to coils of human hair. Since the rudimentary IUDs were expelled too easily, he decided, in 1933, to modify the Gräfenberg Ring (of which he had heard but never seen). He stiffened the Silver Ring by providing it with a central disc attached to the outer ring by spokes. Dr Ota called his silver or gold IUD the 'Precea Ring', ‘precea' being Anglo-Japanese for 'pressure'. The Pressure Ring was to remain popular in Japan well into the 1980s. Less well-known is that Dr Ota may have been the first physician to devise a plastic IUD. However, the inferior quality of plastic material put at his disposal ruined the idea."