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Practice Clinical Opinion

Polycystic ovary syndrome: why widening the diagnostic criteria may be harming women

BMJ 2021; 373 doi: (Published 16 April 2021) Cite this as: BMJ 2021;373:n700
  1. Tessa Copp, postdoctoral researcher1,
  2. Jenny Doust, general practitioner and clinical professorial research fellow2,
  3. Kirsten McCaffery, principal research fellow1,
  4. Jolyn Hersch, early career fellow1,
  5. Jesse Jansen, senior research fellow,, honorary associate31
  1. 1University of Sydney, Sydney, Australia
  2. 2University of Queensland, Brisbane, Australia
  3. 3Maastricht University, Maastricht, Netherlands
  1. Correspondence to: T Copp tessa.copp{at}

This article is adapted from a piece that appeared on BMJ Opinion on 30 March 2021 (

The 2018 International Guidelines1 for polycystic ovary syndrome (PCOS) were intended to standardise diagnosis and improve care, but they also endorsed the controversial Rotterdam diagnostic criteria. These include a larger pool of individuals than alternative definitions and turn many more women into PCOS patients. A growing body of research2 shows that labelling some women with this condition can have harmful, lifelong consequences.

An increase in prevalence

The previous 1990 National Institutes of Health definition of PCOS required both (a) oligo-/anovulation (eg, irregular menstrual cycles) and (b) signs of hyperandrogenism (eg, excess hair growth, acne, or excess male hormones/androgens). The 2003 Rotterdam3 definition added a third criterion: (c) polycystic ovaries on ultrasound (enlarged ovaries with lots of small follicles), but required only two of the three criteria to meet the definition. This introduced four categories or subtypes that now fall within the scope of the PCOS label (a+b, b+c, a+c, and a+b+c) and dramatically increased prevalence (estimates doubling from 9% to 18%4 in Australian women aged 27-34). The 2018 guidelines1 made several minor modifications to the Rotterdam …

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