I personally believe its a sin to do that based on what i've been taught growing up. But i'm in no position to judge anyone who would opt for that and resort to such thing. She probably has a valid reason for deciding to do so or it could be a matter of life and death. After all, we all have been given the freedom of choice and we all know the consequences that will come out from the decision we make as well. However, one mistake cannot be corrected by another mistake. You can advice her not to go through with it, but in the end, it's all up to her to decide for herself, after all, she herself will either suffer or benefit from the choice she make. It's between her and her conscience/faith/belief.