NHS - Phobias:
"..... phobias are more pronounced than fears. They develop when a person has an exaggerated or unrealistic sense of danger about a situation or object...."
I don't think that many, or even any of us on MN, have an exaggerated or unrealistic sense of danger when confronted by a transgender person, either in real life, or by seeing a picture of them. So very few of us will be truly "transphobic".
However, if I was in a ladies toilet or changing room when there was no-one else there apart from an obvious transgender woman and me, I admit that I could feel some concern, even fear, depending on their demeanor or size, but as quoted above, fear on it's own dies not count as a phobia. If I did feel any fear I don't think I should be vilified over it, as it is a fact that some men have pretended to be a transgender female for the sole reason of assaulting women.
I would never fear a photo of a transgender female, but I did find the one of the pregnant one distasteful, because of what it represents. I believe that only women can, and only women should, be able to grow a baby in their womb. If that changes, then so does what makes a woman a woman.
Surely I am entitled to feel like that, and whether it is 'fair' of me or not, to feel like that, it is how I do feel, and not many of us would find it easy to change our instinctual or gut feelings, and in this particular case, I don't want to.
I wonder if my post will be deleted? It shouldn't be, as I have said nothing that could be considered to be against the Mumsnet site's rules.