Just to clarify, when the Trust say they are using these new in addition to referring to referring to women, they mean on everything that a trans person might read, not just one on one when meeting with a pregnant transman.
For example their BSUH's website now includes things like:
"It is recommended that all pregnant women and people take 400 micrograms (mcg) of folic acid each day."
"There is lots of information available for pregnant women and people online."
"Research shows slightly different expected outcomes for women and people having their first baby and those having their next baby."
I think the new language is likely to confuse people, especially those with a poor grip on English/without much medical knowledge. If you are non-binary or trans and want to get pregnant, then I think you should have to accept that there will be a certain amount of references to "women" etc. during the process, because it is only people who are biologically female who get pregnant.