Della:
If she was not a baptized Christian when she had the abortion she incurred no excommunication from the Church to which she did not belong. If she wants to become a Catholic and is a baptized Christian, she will have to confess this sin before being confirmed in the Church.
If she wasn’t baptized, she won’t have to confess anything. Any and all sins she ever committed would be erased at her baptism.
If she were a baptised Christian, but not Catholic, it’s possible she would need to confess the sein. However, if she was truly unaware that there was anything wrong with taking the prescribed pills after being raped, she probably didn’t commit any sin.
It’s not clear that she had an abortion. It sounds like she was given the morning-after pill. While a dose of the morning-after pill can prevent implantation, it can also act as a simple contraceptive. Granted, it’s impossible to determine which may have actually happened in the case at hand, but it’s not clear to me that this would be considered directly procuring an abortion, as per canon 1398.
Even if it were considered abortion, and the individual were Catholic, canon 1329 says that a woman would
not be excommunicated if she were under 17, ignorant of the penalty for abortion,
or acted under compulsion of grave fear.