The Sullivan Review (2025) is an independent review commissioned by the UK government to assess how sex and gender identity are recorded in public data, statistics, and research. Led by Professor Alice Sullivan, the report identifies major issues in data collection practices and provides recommendations to improve accuracy and reliability.
Key Conclusions:
1. Importance of Recording Biological Sex
The report emphasizes that public bodies must collect data on biological sex separately from gender identity to ensure accurate statistics for policymaking. It highlights that sex-based data is crucial for analysing inequalities in healthcare, education, the economy, and criminal justice.
2. Current Data Collection Problems
Many institutions, including the NHS and Police Scotland, have replaced sex with self-identified gender in their records, leading to significant errors. For example:
• The NHS’s failure to record biological sex has led to missed cancer screenings, as trans patients may not receive appropriate screenings based on their birth sex.
• Police Scotland records gender identity without requiring evidence, creating inaccuracies in crime statistics, particularly in data on violence against women.
Other institutions have attempted to capture both sex and gender in inaccurate ways. For example, by attempting to elicit both data sets from a single blended question.
The Review also identified significant safeguarding concerns about current NHS policies of issuing new NHS numbers and records for people when they request for their recorded gender to be changed. At the time of the review, this could be done upon request (no requirements) at any age, including children.
Following the Review’s publication the Secretary of State for Health, Wes Streeting, banned the practice of changing the sex marker on children’s medical records.
3. No Legal Barrier to Collecting Sex-Based Data
The authors report that some institutions began to avoid collecting sex data partially for fear of legal repercussions. However, the review clarifies that there is no legal restriction preventing public bodies from recording biological sex. The report states that misinterpretations of laws such as the Equality Act 2010 have led to unnecessary avoidance of sex-based data collection.
4. Impact on Research and Policy
Inaccurate data on sex has resulted in flawed research and poor policy decisions. The report warns that without clear sex-based data:
• The pay gap between men and women cannot be measured properly.
• Medical research is compromised, as biological differences affect responses to drugs, diseases, and treatments.
• Educational attainment gaps between boys and girls may be obscured.
5. Recommendations for Public Bodies
The report proposes that all government agencies and research bodies:
• Record biological sex by default, and additionally record gender identity or transgender status where necessary for the purpose of the data set.
• Record sex and gender identity separately in all datasets.
• Review existing data policies to ensure biological sex is correctly recorded.
• Train staff on the distinction between sex and gender identity to prevent further confusion.
Overall, the Sullivan Report stresses that accurate data collection is essential for evidence-based policy and public service provision. It calls for immediate action to prevent further deterioration in statistics and research due to the conflation of sex and gender identity.
What Next?
The Health Secretary has already said he will act on the findings of the Sullivan Review as public services should have accurate information on biological sex, especially when it comes to healthcare. CAN-SG has written to Wes Streeting thanking him for moving swiftly on accurate recording of sex in children’s medical records and urged him to ensure that this is promptly extended to adult medical records.
View the full report on gov.uk
Incoherent and Unsafe
Prior to the publication of the Sullivan Review a detailed report about the risks of unreliable sex data in medical records was published by Women’s Rights Network, SEEN in Health and CAN-SG: Incoherent and Unsafe: How the NHS’s Failure to Reliably Record Sex Puts Patients at Risk. Its findings are consistent with those of the Sullivan Review about the importance of accurate sex data in medical records
References
Sullivan, A. (2025) Independent Review of data, Statistics and research on sex and gender, GOV.UK. Available at: https://www.gov.uk/government/publications/independent-review-of-data-statistics-and-research-on-sex-and-gender (Accessed: 9 April 2025).
Keilthy, V. (2025) Incoherent and unsafe: How the NHS’s failure to reliably record sex puts patients at risk. rep. Women’s Rights Network, SEEN in Health and the Clinical Advisory Network on Sex and Gender. Available at: https://assets.ctfassets.net/p9eb47dy7bbi/3nM32mBm7XJeM5lfP0CFiE/0ef3e76d5d4de7d63348d79b336d9b45/2025-03-11-incoherent-unsafe-WRN-SiH-CAN-SG-report.pdf (Accessed: 13 April 2025).