Primodos was a hormone-based pregnancy test used in the 1960s and 1970s that consisted of two pills that contained norethisterone (as acetate) and ethinylestradiol. It detected pregnancy by inducing menstruation in women who were not pregnant. The presence or absence of menstrual bleeding was then used to determine whether the user was pregnant.
First made available for sale in the UK in 1959, it was withdrawn from sale in the UK in 1978.
Primodos was produced by Schering AG, a German company taken over by Bayer AG in 2006.
Another hormonal pregnancy test called Duogynon was in use in Germany during the same general time period.
Claims of adverse effects
There are disputed claims as to whether Primodos may have been the cause of birth defects. A review by the Committee on Safety of Medicines in the 1970s concluded that the product should not be used by pregnant women. Litigation in the 1980s regarding these claims ended inconclusively, with proceedings being discontinued, with the court's approval. A review of the matter by the Medicines and Healthcare Products Regulatory Agency in 2014 assessed the studies performed to date, and concluded that it found the evidence for adverse effects to be inconclusive.