"If my country would be OK ... I would not try to cross," said a mother from Honduras hoping to cross the U.S. border with her 7-year-old son.
American, United, Frontier and Southwest made the requests after social media posts described groups of terrified, crying children on flights.
"Are we a nation that accepts the cruelty of ripping children from their parents' arms, or are we a nation that values families?" the former president wrote.
At the current rate, family detention centers could be full after only eight days. And there are no plans to reunite those families that have already been separated.
The removal was one of several changes made to the WHO's International Classification of Diseases, a manual used by doctors in most countries around the world.