I get your point, but I agree with above, exercising in a safe way depends on who the mum is, and how the pregnancy is going. It's very unfair to think that mums who don't exercise do it by choice. However, t's not pushing in people' s face something you are proud of achieving, and rightly so.
you could go further, putting news about pregnancy and baby is going to hurt or offend someone too. You should be able to put anything on your own social media, if people don't like it, they are free to unfollow.
I have knows some athletes who barely had to slow down before and just after birth, I have seen others who were put on bed rest and could barely walk for weeks after a bad birth. Pregnancies are not fair or equal at all.
Showing women who can that, yes, it can be done, you can get up and move, keep your body, or work to have it back, it's a good thing. Having a baby is not a curse, you can go back to run marathons and wear bikinis not long after (if you are lucky), or much later (if you are not)