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Performance, Inclusion and Elite Sports – Athletes with Differences in Sex Development

A POSTnote giving an overview of the scientific and ethical debate around policies regulating the participation of female athletes with differences in sex development (DSDs) in the female category of elite, professional sports.

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Differences of sex development (also known as intersex, variations of sex characteristics or disorders of sex development) is an umbrella term for a wide range of traits that differ from typical sex development, including chromosomal, anatomical, hormonal or gonadal sex. Certain DSDs can result in a female individual having naturally elevated levels of testosterone. As the hormone testosterone is known to confer an athletic advantage when administered as an anabolic steroid, a key question is whether female athletes with DSDs have a performance advantage over female athletes without DSDs. Some international sports organisations, such as World Athletics and FINA, require female athletes with certain DSDs to reduce their testosterone levels in order to compete in the female category, to maintain fairness of competition. However, such regulations are contested by many on scientific and ethical grounds.  

Key points

  • Some types of DSDs can result in female individuals having naturally high levels of testosterone.  
  • Testosterone is known to drive increases in muscle mass, strength, and endurance when given as an anabolic steroid. However, research is conflicting about whether having naturally high levels of testosterone correlates with increased performance advantage.  
  • World Athletics and FINA are two international sports organisations that regulate the participation of female athletes with DSDs in the female category of sport by imposing a testosterone limit. Testosterone suppression can be achieved through medication, or in some cases surgery. 
  • Difficulties with studying the relevant population means that there is limited direct research on any performance advantage.
  • Regulations aim to maintain a level playing field in the female category. However, many groups regard them as breaching international human rights standards, through discrimination, bodily harm, and right to privacy.
  • World Athletics’ regulations have been shaped partly by legal cases relating to human rights issues raised by athletes. Most recently, South African runner Caster Semenya unsuccessfully appealed the regulations at the Court of Arbitration for Sport, which ruled that the regulations were discriminatory but were proportionate in maintaining fair competition in the female category. Semenya is in the process of pursuing a case at the European Court of Human Rights.
  • In 2021, the International Olympic Committee suspended their previous regulations requiring female athletes with DSDs to suppress their testosterone levels. They replaced these regulations with a new framework advocating for the prioritisation of human rights of athletes with DSDs, and delegating responsibility for creating regulations to individual sports organisations. 


POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer-reviewed. POST would like to thank consultees and peer reviewers for kindly giving up their time during the preparation of this briefing, including: 

Professor John Brewer, University of the West of Scotland* 

Morgan Carpenter, Intersex Human Rights Australia*

Jonathan Cooper, University of Gloucestershire* 

Government Equalities Office* 

Joanna Harper, Loughborough University* 

Professor Richard Holt, University of Southampton* 

Dr Payoshni Mitra, Global Observatory for Gender Equality and Sport* 

Dr Seema Patel, Nottingham Trent University*  

Professor Roger Pielke, University of Colorado Boulder* 

Professor Yannis Pitsiladis, University of Brighton*  

Professor Alun Williams, Manchester Metropolitan University*  

World Athletics* 

*denotes people and organisations who acted as external reviewers of the briefing.

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