What is the ruling of Islamic law concerning the abortion of a malformed fetus in its fifth month, based on the advice of doctors? And is anything incumbent upon the one who performs it?

Abortion is not permissible except in two specific cases. Whoever carries out an abortion outside of these two cases, whether an individual or a group, must repent to Allah and pay the blood money (diyah), which is the value of a male or female slave, or one-tenth of the blood money of a free woman, to be given to the heirs of the fetus. Any heir who participated in the abortion has no right to this payment. They also owe expiation (kaffarah), which is freeing a believing slave; if unable to find one, then fasting for two consecutive months. Examples of direct participation include a doctor injecting a woman with something that causes a miscarriage, or a woman herself taking something that causes it. As for the indirect cause, they must repent to Allah.