Hayden Cross is putting gender surgery on hold to become the UK's first trans male to give birth
The astonishing warning comes in official guidelines issued by the British Medical Association to its 160,000 members, which says mothers-to-be should be referred to as 'pregnant people' instead.
The controversial advice to doctors in hospitals and general practice comes just weeks after it emerged that a Briton who was born a girl but is changing to a man put his operation on hold to have a baby.
Four-months pregnant Hayden Cross, 20, is legally male and has had hormone treatment but not sex-change surgery.
There are no other known cases of a transitioning person becoming pregnant in the UK, but official figures show 775,000 women give birth in Britain every year.
Despite this, the BMA insists doctors should drop the word 'mother' when referring to pregnancy to avoid offending transgender people and to 'celebrate diversity'.
The contentious call is made in a 14-page booklet called A Guide To Effective Communication: Inclusive Language In The Workplace.
It says: 'A large majority of people that have been pregnant or have given birth identify as women. However, there are some intersex men and trans men who may get pregnant.
'We can include intersex men and trans men who may get pregnant by saying "pregnant people" instead of "expectant mothers".'
In an introduction to the guide on the BMA's website, senior executive Dr Anthea Mowat wrote: 'I would encourage you all to read and share this guide, and think about how you can apply it in your day-to-day work. This is a time where we need to come together to support and protect our colleagues and our patients.'
But last night women's campaigner Laura Perrins criticised the BMA's advice as 'anti-science, anti-women and anti-mother'.
She said: 'As every doctor knows only females can have children. To say otherwise is offensive and dangerous. This will offend women up and down the country, and is an example of the majority of women being insulted for a tiny minority of people.'
Conservative MP Philip Davies described the guidance as 'completely ridiculous', adding: 'If you can't call a pregnant woman an expectant mother, then what is the world coming to?'
The guide also tells doctors that they should not use the terms 'born man' or 'born woman' in relation to trans people, as these phrases 'are reductive and over-simplify a complex subject'.
Neither should they say 'biologically male' or 'biologically female', for the same reasons. Instead, they should say the individual was 'assigned' or 'designated' male or female at birth.
Michael Nazir-Ali, the former Bishop of Rochester, said: 'I think it is sad that society is being pushed in this direction. God has made us man and woman, and mothers relate to their children in different ways than fathers. This ruling will confuse people about the vital role of mothers in bringing up their children.'
And the Roman Catholic Bishop of Portsmouth, the Right Reverend Philip Egan, warned it would cause 'great confusion and harm'.
He said: 'It is Orwellian, isn't it? Another example of people trying to control our thoughts and the way we speak.'
However, Heather Ashton, of the transgender support group TG Pals, said: 'We know that biological females are the pregnant ones but trans people are parents too, and this is massive step forward to prevent discrimination against them. The fact that the terminology is changing can only be a positive thing for everyone who wants to be a parent and has the right to be a parent.'
Meanwhile, The Mail on Sunday has also discovered that the Department of Health has issued formal orders that trans women - those who were born male but identify as women - should be routinely accommodated on female single-sex wards. Similarly, trans men should be placed on male wards.
In a missive to hospitals they say: 'Trans people should be accommodated according to their presentation: the way they dress, and the name and pronouns they currently use. This may not always accord with the physical sex appearance of the chest or genitalia.'
There are now 53 charities and pressure groups dedicated to promoting the rights of transgender people - many receiving public funds.
And hundreds of thousands of pounds of public money is being spent on research looking at how everyday terms such as 'boys and girls' might 'exclude' transgender individuals.
Handouts include £50,000 given to Sheffield Hallam University for a study into 'discriminatory' toilet signs, which recommended that 'ladies and gents' signs be replaced with 'toilets with urinals' and 'toilets without urinals' signs. More universities are introducing 'gender neutral' toilets - at least 11 of Oxford's 38 colleges have done so - while students elsewhere have campaigned for sanitary towel bins to be placed in men's bathrooms to cater for trans men.
The BMA's booklet on inclusive language does not only cover transgender rights. It also argues against male-centric language - so advises members to use the phrase 'family name' instead of 'surname... which may originate from sire-name, the name derived from one's father.'
But many linguists think 'surname' actually derives from the Anglo-French 'sornom' or 'surnoun', meaning 'over-name'. The guide also advises that 'gender neutral language' should be used 'until you know what terms they prefer'.
The BMA insisted: 'This is a guide for BMA staff and representatives aimed at promoting an inclusive workplace at the BMA.
'It is not workplace guidance for doctors, which is clear from the fact it does not refer to patients.'
The British Medical Association's recommendation for doctors to avoid the phrase 'expectant mothers' is just the latest assault on womanhood by the transgender lobby.
The BMA is one of the many institutions now fearful of acknowledging the realities of the biological differences between the sexes, at the risk of offending transgender people.
Trans-activists are enjoying huge success in their campaign to re-invent our language so that every aspect our lives becomes 'gender neutral' - from pregnancy down to lavatory habits. As this newspaper reported last weekend, Girlguiding now describes itself as a 'single gender' body. In America, the term 'chestfeeding' is gaining cachet as an alternative to breastfeeding for women who have babies before transitioning.
Midwives in the US are also being directed to use terms such as 'front-hole' instead of vagina, and 'window-birth' rather than caesarean section, in case trans-people are offended. And it is only a matter of time before these linguistic trends find their way across the Atlantic.
At the same time, significant amounts of money are being spent by our institutions to avoid being accused of transphobia, while services supporting women and children escaping domestic violence are cut to the bone.
The National Union of Students, for example, is employing a full-time transgender officer on a salary that is likely to be in excess of £20,000. It is no wonder that so many women are angry and upset about the erasure of their identities to the point where they are being told it is transphobic to even use the correct language to describe our reproductive systems.
Or would that be deemed offensive to the dead, or to rocks, or even dead rocks ?
Would anybody be offended if I said that the BMA are 'cognitively challenged' ?