A pregnancy drug used by thousands of mothers in the 1960s and '70s greatly increased the chances of birth defects, a new investigation has revealed.
Primodos worked by inducing menstruation in women who weren't pregnant. If a woman was only recently impregnated, it worked similar to a morning-after pill to end the pregnancy.
If no menstruation occurred after taking the pill, it was a sign the woman was pregnant.
First prescribed in the UK in 1959, by the 1970s there were fears it was the cause of a number of abnormalities. It was withdrawn in 1978 but not for safety reasons - the arrival of urine tests rendered it obsolete.
Court cases over its effects collapsed due to a lack of evidence, but a Sky News investigation has found documents suggesting a cover-up occurred.
Professor William Inman, a medical officer for the UK government, discovered women who took Primodos were five times more likely to give birth to a disabled child than other mothers. His research was given to Primodos manufacturer Schering-Plough - but never made public.
Files kept in the Berlin National Archives also show the British medical regulator was first notified of the link between Primodos and birth defects as early as 1967.
"This is only the tip of the iceberg," Labour MP Yasmin Qureshi told Sky News.
"I think there's thousands out there who have disabilities as a result of this drug."
Ms Qureshi has long campaigned for an inquiry into Primodos and Schering-Plough, which is now owned by Bayer.
Bayer has denied the link, saying it was "not responsible".
"Since the discontinuation of legal action in the UK in 1982, no new scientific knowledge has been produced which would call into question the validity of the previous assessment of there being no link between use of Primodos and the occurrence of congenital abnormalities," it said in a statement.
"Based on the facts and on the law, Bayer does not accept that Primodos was responsible for causing congenital abnormalities."
Campaigners have compared Primodos to thalidomide, which saw tens of thousands of babies born with limb deformities and brain damage in the mid-20th century.