Making the process to obtain a gender recognition certificate easier could lead to more people missing vital medical screenings, an academic has claimed.

Professor Alice Sullivan, head of research at the UCL Social Research Institute, suggested that proposals to make the process for trans people to obtain a gender recognition certificate easier could have “unintended consequences”, including “erasing” sex as a protected category.

The Scottish Government has published plans to update the process for trans people to obtain a gender recognition certificate – including reducing the lower age limit from 18 to 16-year-olds and ending the requirement for a psychological examination and a diagnosis of gender dysphoria.

A human rights watchdog has insisted that people being able to self identify "has emerged as the necessary human rights standards".

Read more: Scottish Human Rights Commission refutes claims gender reforms threaten single sex spaces

But Professor Sullivan told Holyrood’s Equalities, Human Rights and Civil Justice Committee that opening up the ability to obtain a certificate to a larger number of people could have implications on data and also potentially lead to people missing out on the correct health screenings – despite MSPs also hearing evidence from a trans woman who says she has not missed out on medical checks.

The academic said that the original 2004 legislation was “designed to cater to a tiny number of transsexual people suffering severe psychological distress”.

Professor Sullivan added: “The Act was not intended to raise barriers to the collection of data on sex. Yet this has been one of the unintended consequences of the legislation.

“Public bodies have taken the message from the wording from section 9 that people can switch legal sex over their lifetime, not just for certain legal purposes but completely. Section 22 of the act has led to over caution on the collection of data on sex.”

She said that politicians should acknowledge the “likelihood” that “introducing gender self-declaration in law will reinforce an existing reluctance to ask about sex”.

Professor Sullivan said: “We are opening up what was a very small group of people suffering particular psychological distress, to a potentially much larger group of people and a more diverse group of people.

“That does have implications for data collection. It decouples biological sex and legal sex for a larger group of people.

“We don’t know how many and we don’t know how they will be distributed in the population. When organisations choose to collect legal sex rather than biological sex, the impact will be much larger.”

She claimed that the ability to self identity could mean “not having screenings that we are not being called in for” in medical terms, despite a gender recognition certificate having no bearing.

Read more: Warning trans people could face 'malicious' claims to revoke gender certification

Greens MSP Maggie Chapman warned Professor Sullivan that the committee is “not considering how medical records are stored or held or used or how different lists for different screening processes are managed”.

Ms Chapman said: “The process of recording that information in the medical records can already happen and actually the process for getting a gender recognition certificate has nothing to do with those records.

“I’m just wondering why you think that is relevant if the Bill we are looking at is about the process for getting a GRC rather than how medical records are recorded.”

But Professor Sullivan insisted that “medical screening occurs according to the gender marker in your records”.

She said: “We know there have been cases of people not receiving appropriate screening because their gender marker is reflecting their gender identity and not their sex.

“My worry is that by introducing gender self-identification, often what we’re doing is actually erasing the category of sex and that has particular implications for women and girls.”

MSPs also heard from Robin White, a barrister at Old Square Chambers, who has transitioned into a woman.

She told the committee that she had not missed out on screenings and was still being flagged up with examinations needed.

MSPs also took evidence from Victor Madrigal-Borloz, The United Nations’ independent expert on protection against violence and discrimination based on sexual orientation and gender identity.

He stressed that “legal recognition of gender identity is a key to ensuring the deconstruction of institutional and social drivers of discrimination and violence”.

Ian Duddy, the chair of the Scottish Human Rights Commission insisted that “self determination has emerged as the necessary human rights standards”, adding that evidence shows that the “process must not require a medical diasgnosis” to obtain a gender recognition certificate.

He added: “The changes set out in this bill will bring Scotland closer to satisfying international legal standards and will not jeopardise the rights of others.”