Intended for healthcare professionals


Facilitating participation in clinical trials during pregnancy

BMJ 2023; 380 doi: (Published 06 February 2023) Cite this as: BMJ 2023;380:e071278
  1. Nicola Vousden, academic public health registrar1,
  2. Richard Haynes, professor of renal medicine and clinical trials12,
  3. Sarah Findlay, public contributor3,
  4. Peter Horby, professor of emerging infections and global health4,
  5. Martin Landray, professor of medicine and epidemiology2,
  6. Lucy Chappell, professor of obstetrics5,
  7. Marian Knight, professor of maternal and child population health1
  1. 1National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
  2. 2Medical Research Council Population Health Research Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
  3. 3London, UK
  4. 4Nuffield Department of Medicine, University of Oxford, Oxford, UK
  5. 5Department of Women and Children’s Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, UK
  1. Correspondence to: M Knight marian.knight{at}

Nicola Vousden and colleagues call for wider inclusion of pregnant women in clinical trials to increase access to safe and effective treatments and reduce inequity in outcomes

For decades, pregnant women have been routinely excluded from pharmaceutical trials because of widespread concern about drugs harming the fetus. Indeed, although medication use while pregnant or breastfeeding continues to be widespread,1 medication safety and efficacy data during pregnancy are still scarce. A 2011 review of 172 drugs approved by the US Food and Drug Administration from 2000 to 2010 found that 98% had an “undetermined” teratogenic risk in pregnancy, with 73% labelled as having no safety data in pregnancy.2 This striking lack of data means most pregnant women and their clinicians have to take decisions on starting or continuing medicines during pregnancy with very little or no evidence on safety or efficacy to guide their decision. UK confidential inquiries into maternal deaths repeatedly identify women who have died because medications have been stopped, or never started, in pregnancy as a result of unfounded safety concerns.3

In many ways, the covid-19 pandemic did not buck this trend, as nearly all vaccine and therapeutic trials excluded pregnant women. As a notable exception, the Recovery trial was one of few treatment trials for covid-19 that included pregnant women where appropriate, quickly addressing each barrier to inclusion to ensure participation was safe, following appropriate ethical and regulatory review. The trial was rapidly established in March 2020 using a pragmatic unmasked factorial design, and since then it has examined 20 treatments for covid-19 in patients admitted to hospital to assess their effect on all-cause mortality at 28 days after randomisation.4

After decades long efforts to promote inclusion of pregnant women in research, but particularly clinical trials,5 our successful experience in the Recovery …

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