Earlier quoted context omitted.
Literally the only reason to tell a prospective employer about your pregnancy status is to enable them to unlawfully discriminate against you based on that status.
OK but why should a company hire someone if they are almost "immediately" going to be put on paid leave? edit: Yes, downvotes will change my mind. You're all doing a wonderful job and are definitely morally superior to me and I'm unworthy of your keystrokes.
In the United States, there are many people who are in the reserve of the military, or in the National Guard. They often need to take some amount of time away from work for regular training and refresher sessions with the rest of their unit, in order to stay ready for wartime or domestic-emergency (since they also play a large role in responses to natural disasters) duty.
As a society, we've decided this is important enough to our future security to make it illegal to discriminate in hiring against someone who has obligations as a member of the reserves or National Guard, illegal to fire them for taking time away from work to fulfill those obligations, and illegal to force them to use their ordinary vacation time to cover that time away. And even if a reservist or Guard is called to extended active service, they have the right to return to their previous employer so long as that service does not exceed five years.
We've made that choice because, for each individual employer, the temptation is strong to let some other sucker hold a spot for a Guard or reservist, and not waste any of your business' money on them. Which is a tragedy of the commons situation.
Children are similarly an issue of security for our society. There is significantly less point to building things today, if nobody will be around tomorrow. So we, as a society, have also decided that employers cannot discriminate on the basis of choosing to have children.
You seem to have a problem with the second of these. Do you also have a problem with the first? If so, how do you find a consistent position that reaches those two different conclusions?