Well, the beauty of fanfic is that we can. The reality of the law in our country is that she can.
What indication do we ever have, up until season 4, that would lead someone to believe that Lois wants a child? From the beginning, she's presented as a career - driven woman of the '90s who came from a broken home. She can't even keep a plant alive. In this story, she was raped one month ago, and it will take a lot longer than a month to process those feelings. She slept with Clark once - she's really just getting to know him. Tell her that she might be having an alien baby and she'll more likely have nightmares than fantasies.
Point is, I could easily believe that Lois would terminate this pregnancy in this story's situation. I could easily also believe that she'd make a different choice. The lady or the tiger?
That's why I really like this story - it's balanced on a very interesting question.
