Doctors in Germany told the makers of Primodos that it was widely being used to terminate unwanted pregnancies.
Thousands of women in the UK used the drug in the 1960s and 1970s. Research at the time suggested the drug could be linked to a higher risk of women giving birth to babies with abnormalities, but this alleged link has been denied by the manufacturer.
It is feared that others who took the pills to find out if they were expecting may have caused their embryo to die without realising.
On Sunday, Sky News revealed that in January 1975 the British regulator warned manufacturers Schering of a five-to-one risk that the drug could cause malformations.
But we can now bring to light documents extracted from National Archives in Berlin that appear to show the drug’s makers were discussing a very different purpose to what it was being used for in the UK.
In Germany, where the drug was called Duogynon, the papers show that manufacturers noted in 1978 that “during talks about Duogynon it turned out that a surprisingly high proportion of doctors swear by Duogynon to achieve abortion”.
Another Scherings letter from the Berlin files discussing Primodos suggests that in South Korea pregnant women who did not want to keep their baby used the drug, perhaps as a double dose, to abort the foetus.
The letter reads: “Women who don’t accept the pregnancy, mostly employed in entertainment, however, first turn to pharmacists for a substance to provoke a bleeding.”
The file suggests that in South Korea, termination was the most common use for the drug.
It is thought Primodos was given to 1.5 million women in the UK.
Not all of them would have used it as a pregnancy test as it could also be used to regulate periods.
But when the drug was introduced, it was said to provide proof of pregnancy much more cheaply than the method used at the time – injecting toads with a woman’s urine.
Instead, Primodos was said to induce a period if the woman was not pregnant.
It is now known that one dose of the drug contained super-strength hormones that, later, would be used in the morning-after pill.
If a woman was pregnant, these large doses of progesterone would, it was thought, simply be absorbed into the body. If she wasn’t, they would trigger menstruation.
But the concentration was extremely high in today’s terms. One dose of Primodos equates to 13 morning-after pills or 40 oral contraceptive pills.
In 1975 regulators placed a warning on the packet that it should not be used during pregnancy.
Sky News has also discovered that before the drug went on the market a Schering executive suggested: “For psychological reasons it does not seem appropriate to point out abortion as a usage too much in the leaflet for Duogynon (Primodos) or even have the word ‘abortion’ appear, as we can assume with certainty that abortion will play a big role.”
Recent tests conducted in Aberdeen by embryologist Neil Vargesson on fish embryos, seen by Sky News, show how the drug has the potential to deform.
In early development, fish and human embryos are similar. His experiments have demonstrated the drug can cause defects in an animal’s fins and spinal and heart problems, and have also found the compound has the ability to kill fish embryos.
Dr Vargesson told Sky News: “We’ve seen that in fish, high doses are embryo-lethal.
“They are slightly higher doses than you’d see in humans because we are adding it into water, but we’ve also got a dose response. Lower doses don’t do anything. Higher doses are quite nasty and, then, doses in between give you damage.”
This does not prove it would do the same in humans – but it does show the drug has the potential to deform if it is able to cross the placenta, which protects a baby in the womb.
Victims who claim to have been damaged by Primodos are preparing to take legal action against the pharmaceutical company Bayer, which took over Schering in 2006.
Sky News has met dozens of families with children born in the 1960s and 70s who say they have been affected by Primodos, which was removed from the UK market in 1978.
Some children have physical deformities such as shortened limbs or spinal defects.
Other parents miscarried or lost their children due to congenital problems such as heart defects.
Robin Hayes, whose son died aged 10 after being born with life-threatening heart problems, told Sky News: “I’m convinced, and I will be until my dying day, that this drug was responsible for the death of my son.”
Bayer have told Sky News that Primodos was on the market in the UK “in compliance with prevailing laws”.
The view at the time and today, after a full review, is that “evidence for a causal association between the use of hormonal pregnancy tests and an increased incidence of congenital malformations was extremely weak”.
The Department of Health has welcomed our investigation and the Sky News documentary is being shown in Parliament on Tuesday.
:: Sky News’ hour-long documentary, Primodos: The Secret Drug Scandal, will be presented by senior political correspondent Jason Farrell, who has been investigating it for six years. It can be seen on Tuesday 21 March at 8pm on Sky Atlantic and on Wednesday 22 March at 9pm on Sky News.