sex-based abortions

Faithful blog readers, I need your help understanding something. My "gender" Google news feed has been blowing up lately with stories regarding the legislation of sex-based abortions. Apparently, such abortions have recently been ruled illegal in Sweden and legal in Oklahoma.

Now, I understand there being concern over sex-based abortions. Technology is advancing at a rate that allows possible potential parents to learn the sex of their fetus earlier and earlier all the time -- often with enough time to legally abort the fetus if they are unhappy with the sex. It is awful that anyone anywhere would value one sex of a fetus over another, and I get why people don't like that idea (I don't like it myself). In fact, we wrote about it a little bit on this very blog a while back.

What I don't understand, though, is how the motivations behind an abortion can be legislated. Isn't that like arresting someone for thoughtcrime? How can the state decide whether or not a pregnant person's motivations are good enough to warrant an abortion? I am seriously confused, so if any of you legal smarties out there have any insight, help a sister out.