Circular spiral silver Grafenberg ring, c.1930
German gynaecologist Ernst Grafenberg (1881-1957) devised this intrauterine device (IUD) in the 1920s. The Grafenberg IUD was a popular contraceptive. Early examples were made of silkworm gut and silver wire. An IUD works after conception. It stops a newly fertilised embryo implanting and growing in the lining of the uterus. It was inserted into the uterus by a physician. It could be left in place for several years.