The document’s glossary defines a “birth parent” as “the parent who gave birth to the baby” – in other words, a mother.

It also refers to “employees who have stillbirths” when addressing women who lose their child after the 24th week of pregnancy.

Then, the policy goes on to snub “gendered language” in favour of “expectant employees”, “employees who are breastfeeding” and facilities for “employees to express milk”.

Women’s rights campaigners have poured scorn on the wording, and have warned of how deeply gender ideology has become embedded in parts of Scotland’s public sector.

They accuse officials of deliberately changing their language to avoid using “woman” and “mother” – even when discussing maternity.

The SPS hails how it uses gender-neutral terminology “as far as possible” to be “inclusive of all families.”

But the guidance comes despite last April’s unanimous Supreme Court ruling – that sex in law refers to biological sex.

The judgment was widely seen as reinforcing clear sex-based definitions, and was hailed as a common sense victory by many.

Critics now say the SPS has disregarded this ruling in its maternity rights document, and say the gender-neutral wording effectively excludes women from their own maternity protections.

They have also condemned the phrasing as “deeply offensive” for failing to explicitly recognise women after stillbirths.

Rachael Hamilton, the deputy leader of the Scottish Conservatives, said: “Women across Scotland will be rightly alarmed that the Scottish Prison Service is continuing to erase mothers and women from maternity protections through this kind of absurd gender-neutral language.

“The Supreme Court ruling was crystal clear that sex in law relates to biological reality, yet public bodies are still bending over backwards to appease SNP-backed gender ideology.”

Fiona McAnena, director of advocacy at Sex Matters, called the policy an “insult to all women”.

She said: “Only women can be pregnant, deliver a baby and breastfeed, and the SPS insults all women by pretending otherwise.”

Mary Howden, the co-director of the Women’s Rights Network Scotland, described the policy as “dehumanising.”

Ms Howden blasted: “Most despicably, even in the harrowing section on stillbirth – where an employee ‘loses their child after the end of the 24th week of pregnancy’ – the policy strips mothers of the recognition of their unique, sexed grief.

“A woman enduring the profound trauma of stillbirth is denied the basic dignity of being acknowledged as a mother who has lost her baby.

“This is institutional cruelty masquerading as inclusion. This robs women of their language at the precise moment they need it most.

“This is not progress – it is the dehumanising triumph of ideology over biology.”

The SPS has previously faced fury over its transgender prisoner policy.

Isla Bryson, a biological man convicted of raping two women, was initially housed in a female prison before public outcry led to a transfer.

A Scottish Government spokesman simply said the matter was operational for the SPS.

The SPS, meanwhile, said: “The SPS maternity and parenting policy has been developed in partnership with our trade union partners and has undergone an equality and human rights impact assessment.

“The policy applies to all staff who are entitled to maternity, paternity, adoption or parental leave.”