It does, in the one particular context where I would be looking at it.
(I understand that this response of mine is unusable for labelling images, without the context that they are displayed and viewed in. That's fine. I'm indifferent wrt. labeling pictures on the internet, for the purposes of lawmaking.)
Consider this. Assume you have a nice big poster "featuring women who are from a culture where partial nudity is normal and not considered sexual". Assume you take it to your workplace, to an office where several ladies work, and you put it on display on the wall of your cubicle. I think the picture will be defined sexual in that context, and most women at the office will be uncomfortable with it. I, as a man, would get an arousal response, and therefore, in that context, I would also immediately feel uncomfortable with the poster (and I would also request that it be removed). Indeed I very frequently disagree with being exposed to arousing impulses, and I may try to protect my senses from that. Either way, such a picture is sexual, most of the time. It does depend on the context, so I guess I agree that without context, classification is futile (lacking sufficient nuance). Assuming some "default Western context" though, I still claim that the picture you are proposing is sexual. The context where that image is not sexual, is that culture where the picture originates from. But we are not that culture.
Again, I'm neither supporting nor opposing politicians in labeling and/or restricting images. I'm only talking about what the pregnant woman's picture in the fine article makes me feel, and what urges it generates in me.