Primodos was a Hormonal Pregnancy Test (HPT) that first became available in the UK in 1959.  In addition to being a HPT it was also licensed for a number of other gynaecological conditions. Primodos contained norethisterone acetate (10mg) and ethinylestradiol (0.02mg) and one tablet was given on two consecutive days to women suspected to be pregnant.  

In the late 1960s a number of studies were published that found an association between use of a HPT during pregnancy and congenital abnormality in the infant. Other studies found no association. Nevertheless, the introduction of alternative tests for pregnancy resulted in the gradual phasing out of HPTs.   

By the early 1970s Primodos was no longer authorised as a HPT and its indication was restricted to secondary amenorrhoea. It was also contraindicated for use in pregnancy. In 1978 Primodos was voluntarily discontinued by the manufacturer for commercial reasons.

The Medicines and Healthcare products Regulatory Agency (MHRA) has reviewed the key evidence on the possible effects of HPTs, such as Primodos, taken by the mother during pregnancy and the subsequent development of the child, this can be viewed below.

Assessment of historical evidence on Primodos and congenital malformationsPDF file (opens in new window) (355Kb)

Page last modified: 09 April 2014