Who told Eric that Jody was pregnant?

Jody herself told Eric that she had been pregnant. The revelation comes in Chapter 9, when Eric went on a date with Jody after visiting Sarah in the hospital.
He and Jody started talking openly while on their date, and she admitted to him that she had been pregnant, and that she had the pregnancy terminated. She revealed that her boyfriend, Mark, dropped her off two blocks from the clinic on the day that she had the abortion, because he did not want to be seen with her there. This left her with feelings of abandonment, anger and sadness.
Earlier in the book, in Chapter 8, Mark had revealed in a class discussion that he was morally opposed to abortion because of his religious beliefs.