Mick Hartley

A BMJ editorial welcoming the Sullivan review – Sex and gender should not be conflated in medical data:

Accurate data are essential to clinical care, research, and health service planning. But in some data sets, the NHS and the wider medical profession have conflated the key demographic variables of sex and gender. This can decrease the integrity and reliability of data and potentially compromise healthcare. A government commissioned independent review led by Alice Sullivan, professor of sociology at University College London, was published in March 2025. It concluded that, for good practice, the “default target of any sex question should be sex”; and questions about gender identity should be asked separately.

Sex (male or female) is determined by gametes at conception with phenotype influenced by chromosomes, hormones, and reproductive organs. A few people are found to have one of a small number of clinically recognised variations in sex development (VSDs) after expert investigation. These individuals nonetheless have a sex, either male or female. Gender, by contrast, is a mutable social construct, defined as “the norms, behaviours, and roles associated with being a woman, man, girl, or boy … and varies from society to society and can change over time.”

The Sullivan review set out to examine how data and statistics are gathered in respect to the recording of sex and gender. It found that sex, gender, and gender identity have become conflated in research and clinical datasets in recent years. This may have occurred because gender has been used as a synonym for sex, with some clinicians, researchers, or administrators misunderstanding the distinctions. But some individuals and organisations have lobbied for gender identity to be collected instead of, not in addition to, sex with deliberate merging of categories….

It's not complicated.