Illegals aren’t under our jurisdiction thus we deport them.
If a British diplomat has a child while living here, that child is NOT a US citizen.
If an American has a child visiting France they are not French citizens.
Foreign diplomats have diplomatic immunity. Immunity means placed outside jurisdiction. Only that removes them from the geography defined realities. French law determines what happens in their jurisdiction. Have to read up on their laws, however irrelevant that is.
It is because they are within US court jurisdiction that they can be deported. You could not deport an illegal in Argentina back to Mexico with a US court decree.
This is not even debatable. It’s the same as McCain born outside the US, but at an American military post.
Illegals are within the legal purview of American courts on US soil. The whole argument is silly. Now, what CAN be done is refuse tourist visas to pregnant women. That is not protected by the Constitution.