Christian anti-persecution charity Release International has described the jailing of 23-year-old Demiana Emad as a "disturbing and disappointing" development.
Ms Emad, a social studies teacher, was arrested after the head of the Sheikh Sultan Primary School's parents association accused her of insulting Islam in May last year.
In June 2013, she was sentenced to pay a £8,200 fine which is about three times the starting salary of a teacher.
Sunday's jail sentence was ordered by the court in response to an appeal filed by the defendant on last year's fine.
Andrew Boyd from Release International told Premier's Marcus Jones on the News Hour that Egypt's new government is failing to protect the country's Christians.