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Baby feet close-up

Oral hormone pregnancy tests such as Primodos, containing ethinylestradiol and very high doses of norethisterone, were given to over a million women from 1958 to 1978, when Primodos was withdrawn from the market because of concerns about teratogenicity.

In 2018, we published our systematic review and meta-analysis:

Carl Heneghan, Jeffrey K Aronson, Elizabeth Spencer, Bennett Holman, Kamal R Mahtani, Rafael Perera, Igho Onakpoya
Oral hormone pregnancy tests and the risks of congenital malformations: a systematic review and meta-analysis
F1000Research 2019; 7:1725

Our systematic review showed that oral HPTs in pregnancy is associated with increased risks of congenital malformations. We found 16 case-control studies and 10 prospective cohort studies, together including 71 330 women, of whom 4,209 were exposed to HPTs.

Exposure was associated with an increased risk of all congenital malformations, as well as congenital heart, nervous system and  musculoskeletal malformations, and the VACTERL syndrome (Vertebral defects, Anal atresia, Cardiovascular anomalies, Tracheoesophageal fistula, Esophageal atresia, Renal anomalies, and Limb defects),

Sky News provides a backstory to the issues that led to our review and how documents were destroyed and information withheld about a drug that may have deformed and killed babies in the womb.


Here is what has been happening since our review was first published:

28 November 2018

Sky news covered the review: "A groundbreaking study from Oxford University has linked the pregnancy test drug Primodos to malformations in babies born to mothers who used the drug."

Research findings presented to All Party Parliamentary Group on Hormone Pregnancy Tests at the UK Houses of Parliament on  the link between Primodos and congenital malformation.

December 2018

Review findings were submitted to The Independent Medicines and Medical Devices Safety (IMMDS) Review,  Chaired by Baroness Julia Cumberlege, and presented on the 29th November, by Carl Heneghan to the review panel:

16 January 2019

At the  Houses of Parliament, Yasmin Qureshi MP, asked direct questions about the review findings at Prime Minister’s Questions.

PM Theresa May said: “ministers are aware of the new study that has come out” and, it will be “looked at very carefully.

To which Yasmin Qureshi responded:

Now Professor Carl Heneghan at Oxford University has published a review of the scientific data that clearly shows Primodos did cause deformities.

“Will the prime minister ensure that any review that’s carried out is independent of the MHRA (Medicines and Healthcare products Regulatory Agency) because we have no faith in them?

Obviously it is an important issue” responded the Prime Minister.

28 January 2019

The Expert Working working Group on HPTs presented evidence to the IMMDS review where they were asked about the Heneghan et al review findings.

28 February 2019 

 Lord Alton of Liverpool debated the Safety of Medicines and Medical Devices in the House of Lords:

‘Meanwhile, a team at Oxford, led by Professor Carl Heneghan, the scientist responsible for identifying thalidomide association, has discovered that pooled data show “a clear association” with several forms of malformation. Professor Neil Vargesson has carried out other work on zebrafish, which revealed anomalies that mirrored the adverse effects on victims of Primodos. Their studies were peer-reviewed and remain in the top percentile of scientific studies.’

Lord Alton brought up requests for the raw data from the EWG report:

"I welcome that. However, the raw data that Professor Heneghan needs to complete his review has not been made available. The All-Party Parliamentary Group on Hormone Pregnancy Tests, chaired by Yasmin Qureshi MP, and of which I am vice-chairman, has sent a freedom of information request for the data, but to date has not received a response."

5 March 2019

We were sent the MHRA’s review of the Heneghan et al systematic review. The questions raised about the review were:

  1. The selection of controls.
  2. The selection of confounding variables across studies.
  3. The analysis from studies that took account of a previous history of congenital malformations.

We posted our response here.

13 March 2019

German Parliament meeting where Jeff Aronson presents the evidence from Heneghan et al systematic review and issues with the animal data.

15 March 2019

BMJ EBM blog post on ‘Assessing bias in studies of harms: a case study of Primodos and congenital malformations’ by Carl Heneghan.

18 March 2019

C Heneghan and JK Aronson discussed the findings of the Heneghan et al systematic review “Oral hormone pregnancy tests and the risks of congenital malformations: a systematic review and meta-analysis”  at a meeting of an ad hoc expert group convened by the Medicines and Healthcare products Regulatory Agency (MHRA) in London.

Update to the association between Oral Hormone Pregnancy Tests, including Primodos, and congenital anomalies

28 March 2019

FOI request data published on CEBM  and sent by email for For the attention of the MHRA, the IMMDS review team, the APPG Primodos and interested parties,

We present a pooled analysis of data that were included in the report of the UK’s Commission on Human Medicines independent Expert Working Group (EWG), based on data obtained through an FOI request. Table 2 shows the striking similarity of the results for the EWG review and the Heneghan et al review for congenital heart defects, any malformations, and urogenital malformations.

Table 2 in the report is a comparison of analyses of the data presented in the EWG report and those presented by Heneghan et al.

Malformations EWG results [2] Heneghan et al results [1]
Congenital heart defects OR = 1.91 (95% CI = 1.36 to 2.68; I2 = 22%; P = 0.0002) OR = 1.89 (95% CI = 1.32 to 2.72; I2 = 0%; P = 0.0006)
EWG: any congenital malformation


Heneghan et al: all congenital malformations

OR = 1.34 (95% CI = 1.13 to 1.60; I2 = 0%; P = 0.0008) (OR) = 1.40 (95% CI = 1.18 to 1.66; P < 0.0001; I2 = 0%).
EWG: genital
Heneghan et al:  urogenital
OR = 2.22 (95% CI = 0.82 to 6.02; I2 = 0%; P = 0.12) OR = 2.63 (95% CI = 0.84 to 8.28; I2 = 0%; P = 0.10)

This finding further adds to strengthen our conclusions as both systematic reviews show that the use of oral HPTs in pregnancy is associated with increased risks of congenital malformations. A copy of this report is available here.

4 April 2019

Sky News Jason Farrell covers the story ‘Primodos review criticised for ‘not assessing risks properly.’

8 April 2019

Written questions asked by Lord Alton of Liverpool of the House of Lords to government ministers:

(HL15086) To ask Her Majesty’s Government what assessment they have made, if any, of the accusations made by Professor Carl Heneghan of the University of Oxford and reported by Sky News on 5 April that a study on Primodos overseen by the Medical and Healthcare products Regulation Agency failed to properly assess the risks of that drug; and that meta-analysis results were left out of the final report.

(HL15087) To ask Her Majesty’s Government what assessment they have made, if any, of reports by Sky News on 5 April that UK regulators in the 1970s destroyed evidence that suggested an association between the use of Primodos and birth defects.

18 April 2019

Expert Working Group report on hormone pregnancy tests briefing report prepared by the House of Commons Library for the upcoming debate:

By Sarah Barber Nikki Sutherland. This pack prepared ahead of the debate to be held in Westminster Hall on 23 April 2019 at 11.30am on the Expert Working Group report on hormone pregnancy tests. The debate will be led by Yasmin Qureshi MP.

A new systematic review and meta-analysis of the research on hormone pregnancy tests was published in November 2018. This concluded that:[…] use of oral HPTs in pregnancy is associated with increased risks of congenital malformations. One of the authors of the study, Professor Carl Heneghan, raised concerns about the 2017 Expert Working group review in an interview with Sky News. He said that there had been a failure to undertake a systematic review.

23 April 2019

House of Commons Debate took place, the full text of the debate is available via Hansard:

Yasmin Qureshi MP: Such is the depth of concern about this issue that there have already been three debates on the expert working group’s review—this is the fourth. Each and every time, Members from across the House have urged Ministers to consider our concerns about the methodology, the independence of the panel members and the conclusions of the report. On each and every occasion, however, our concerns have been dismissed.’

Twelve MPs spoke at the debate:

  • Yasmin Qureshi (Bolton South East) (Lab)
  • Gordon Marsden (Blackpool South) (Lab)
  • Mr George Howarth (Knowsley) (Lab)
  • Bill Grant (Ayr, Carrick and Cumnock) (Con)
  • Emma Reynolds (Wolverhampton North East) (Lab)
  • Sir Mike Penning (Hemel Hempstead) (Con)
  • Hannah Bardell (Livingston) (SNP)
  • Yvonne Fovargue (Makerfield) (Lab)
  • Brendan O’Hara (Argyll and Bute) (SNP)
  • Sir Edward Davey (Kingston and Surbiton) (LD)
  • Jonathan Reynolds (Stalybridge and Hyde) (Lab/Co-op)
  • Paula Sherriff (Dewsbury) (Lab)

The Parliamentary Under-Secretary of State for Health and Social Care (Jackie Doyle-Price), said:

‘I turn finally to the data published by Professor Heneghan. Although this analysis does not contain any new data, it found the use of hormone pregnancy tests in pregnancy is associated with a small increased risk of certain congenital malformations. The Government have therefore asked for a completely new expert group to be convened in order to consider Professor Heneghan’s work, and for a review to be conducted in parallel with the European review. Those reviews are ongoing, and I look forward to receiving that advice.
I appreciate that I have not been able to satisfy all the representations made by hon. and right hon. Members this morning. As I said, the Government will continue to review evidence in this area. We are still considering the evidence from Professor Heneghan, and we look forward to implementing any recommendations that Baroness Cumberlege brings forward in this regard.

6 May 2019

Minutes of the meeting and MHRA assessment report published on the UK Government’s website. An ad hoc Expert Group of the UK’s Commission on Human Medicines (CHM) has considered a systematic review and meta-analysis of studies on oral Hormone Pregnancy Tests published by Heneghan et al.

5 September 2019

Carl Heneghan interviews Marie and Michael Lyon, Lisa Lunt and Jeff Aronson on their investigations at the National Archives in Kew about Hormone Pregnancy tests.

27 November 2019

Marie Lyon wins NIHR School for Primary Care research to EXCEPTIONAL CONTRIBUTION TO PATIENT AND PUBLIC INVOLVEMENT: ‘her passion for the topic stood out and the judges felt she made a very impressive contribution to the field, research project and dissemination of research findings.’

View the nomination letter here.