A new Sky documentary examines the story of Primodos, a hormone based pregnancy test drug used in the 1960s and 1970s, which allegedly caused a range of birth defects. Bitter Pill: Primodos examines the story of the test, and its link to one of the pharmaceutical industry’s biggest scandals. There has been a 40-year-long campaign to raise awareness of the potential dangers of the drug. Talking to Sky News in an exclusive interview, former prime minister Theresea May said that the government should consider “redress” for the victims of the scandal. This is everything you need to know about the Primodos scandal. What is Primodos? Primodos, a hormone based pregnancy test drug, was given to an estimated 1.25 million women in Britain in the 1960s and 1970s A single dose of Primodos contained super strength hormones. Those same hormones would then go on to be used in oral contraceptive pills, but in a much lower concentration. Primodos was made up of two pills of 10mg of norethisterone and 0.2mg of ethinylestradiol. Women were advised to take “one tablet on each of two consecutive days”. The instructions said: “Bleeding follows in three to six (rarely as long as ten) days, if there is no pregnancy. An existing pregnancy is unaffected by Primodos.” It was thought that, if a woman was indeed pregnant, that these large doses of progesterone would simply be absorbed into the body - and if she wasn’t pregnant, then it would trigger menstruation. It was taken off the market by its manufacturer in 1978 as concerns rose regarding the possible association with birth defects. Primodos was manufactured by drug company Schering - now part of Bayer - which continues to deny that the drug caused deformities in children. What was the scandal about? There was some research at the time which suggested that there could be an association between Primodos and a variety of pregnancy issues. These included miscarriages, babies born with shortened limbs, and babies with abnormalities related to their internal organs, brain damage and heart defects. Many of the children affected by the drug died before reaching adulthood - for those still alive, some are blind, deaf and brain damaged. In 1967, Surrey-based pediatrician Dr Isabel Gal wrote a letter to the prestigious science journal Nature, in which she suggested that Primodos was causing spina bifida in children. This was 11 years before the drug would eventually be pulled from shelves. Dr Gal told Sky News that she fought a 10-year battle to have the drug removed from the market, but had been shut down by every institution - from the Department of Health to the Committee on Safety of Medicines. In 1968, statistician Dr Dennis Cook ran a study in which he found that the incidences of birth malformations in the UK rose in correlation with sales of the drug. Dr Cook recommended to the manufacturer that further studies should be carried out. Years later, Dr Cook said he believed that those studies had not been carried out. The Department of Health committee, in 1970, asked Schering, the manufacturer of Primodos, to remove pregnancy testing as one of the uses for the drug. In 1975, a warning then appeared on Primodos packets stating: “May cause congenital abnormalities.” Campaigners argue that these warnings on the packet - and the eventual removal of the drug - was too little too late, especially since the potential link had been revealed 10 years earlier by Dr Gal. Was there a coverup about the scandal? An investigation by Sky News found, in 2017, that evidence of an association between the drug and deformities had been destroyed by a UK regulator in the 1970s. In the Berlin National Archives, it was found that hundreds of files about Primodos were stored unseen for decades. These files showed that, in 1975, Professor William Inman, who was the principal medical officer for the UK government, had found that women who took a hormone pregnancy test “had a relative five-to-one risk of giving birth to a child with malformations”. A later document explained that Dr Inman destroyed the materials upon which his findings were based, “to prevent individual claims being based on his material”. A company spokesman for Bayer said in a statement: “Bayer denies that Primodos was responsible for causing any deformities in children. “Since the discontinuation of the legal action 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 the use of Primodos and the occurrence of such congenital abnormalities.” What has Theresa May said about the scandal? Speaking to Sky News for an interview for Bitter Pill: Primodos, May said: “I think it’s important that the government looks at the whole question of redress and about how that redress can be brought up for people.” While victims of the drug have received an apology, May said that “lives have suffered as a result” of the drug’s use. In the interview, May praised the campaigners who had been “beating their head against a brick wall of the state” which tried to “stop them in their tracks”. In 2017, a review found that scientific evidence did “not support a causal association” between the use of hormone pregnancy tests like Primodos and birth defects or miscarriages. However, May ordered a second review in 2018, saying: “Certainly, when I looked at that report, I felt that it wasn’t the slam dunk answer that people said it was. “At one point it says that they could not find a causal association between Primodos and congenital anomalies, but neither could they categorically say that there was no causal link.” The second review, which concluded last month, found that there had been “avoidable harm” that had been caused by Primodos and two other products - sodium valproate and vaginal mesh. She said: “I almost felt it was sort of women being patted on the head and being told ‘there there dear’, don’t worry. You’re imagining it. You don’t know. We know better than you.” Speaking about the campaigners, May said: “I think this is a very sad example of a situation where people were badly affected, not just by the physical and mental aspect of what Primodos actually did, but by the fact that nobody then listened to them.” When does the Sky documentary air? Bitter Pill: Primodos will air on Sky Documentaries on Monday 24 August, and will last an hour and 45 minutes. The documentary will start at 9pm and will also be available on NOW TV at the same time. The documentary will explore the stories and lives affected by the scandal, as well as campaigners’ fight for answers and justice. The film features Marie Lyon, chair of the Association for Children Damaged by Hormone Pregnancy Tests, and who has been a high profile figure in campaigning for justice after her daughter was born with a severe limb deformity.