To understand why this is happening, you have to go back in history to the end of the slave trade. When the ability to kidnap people from Africa and bring them back to enslave them was legally ended, the white enslavers realized that the only way they could keep slavery going was to force people to breed more slaves. Google that history. It is utterly abhorrent but necessary to understand where the Republican Party is coming from today.
Since the end of slavery, a certain contingent in the U.S. has never gotten over the fact that they couldn’t legally have a sub-class of citizens that they could use for free or nearly-free labor. So they kept trying to find other ways to keep people oppressed, and they expanded that oppression beyond just black people and to any of the “less desirable” groups. Think not just Black people, but also Irish, immigrants, Appalachia. They pit these groups against one another because divided people are easier to control. But the goal is the same - have large groups of people poor for generations who have no other option but to work for slave wages and keep the people at the top very, very rich.
Slavery in the U.S. was a huge economic force, one that a certain contingent (the very wealthy) never got over losing. The next best thing was to create whole groups of people who are desperate enough to work for almost nothing. That’s what we have in this country now. And it works best if those people are constantly putting out more children. That keeps them even more stuck and more desperate, and it keeps a steady supply of cheap labor coming.
It’s no coincidence that they want abortion ended but also want to ensure those same people are continually subjected to sub-standard education, that those same people are “allowed” to send their kids to work (defeating years of progress through child labor laws), that those people are also unable to access higher education, government benefits, or virtually anything that could potentially make their lives better.