I'm not sure specifically if there is a fanfiction exactly about Camie Utsushimi being pregnant. There are so many fanfiction platforms and a vast amount of content out there. You could try searching on popular fanfiction websites like Archive of Our Own or FanFiction.net to see if such a story exists.
Here is a simple toga himiko camie oc fanfic: In the bustling city of Musutafu, there was a new student named Camie. She was a bit of an outcast with her own unique style. One day, she bumped into Toga Himiko. Toga was intrigued by Camie's carefree attitude. They started to hang out more and more. Camie showed Toga her favorite spots in the city, like the hidden cafes and rooftops. As they spent time together, they realized they had more in common than they thought, and a strong friendship began to form.
A more emotional idea would be a story where Camie has lost her memory. Toga Himiko finds her and tries to help her remember who she is. Along the way, they discover secrets about each other and their pasts, strengthening their bond.
One possible plotline could be that Camie discovers she's pregnant unexpectedly and has to deal with the reactions of her friends and family. Maybe some are supportive, while others are shocked or disappointed.