Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Brother, first of all, we’d like to say that we are impressed by your question, which emanates from a thoughtful heart. May Allah Almighty help us all adhere to the principles of this true religion, Islam, and enable us to be among the dwellers of Paradise in the Hereafter, Ameen.
First of all, it is to be stated that Islam forbids abortion in all stages of pregnancy. When the pregnancy reaches 120 days old, abortion becomes totally forbidden and is deemed a form of murder that results in compensation becoming liable. If abortion is done prior to this period, no compensation is liable but one should ask forgiveness and promise never to commit it again. In addition, it is highly recommended to do much righteous deeds such as giving in charity, etc.
In response to the question in point, the European Council for Fatwa and Research, issued the following fatwa:
Indeed, abortion is forbidden in Islam whether it be in the earlier stages of pregnancy or otherwise. The extent of sin incurred varies according to the stage of pregnancy, so that less sin would be incurred if the abortion took place during the early stages, while it becomes increasingly haram (unlawful) as the pregnancy advances. When the pregnancy reaches 120 days old, abortion becomes totally forbidden and is deemed a form of murder that results in compensation becoming liable. This compensation is equal in value to 213 grams of gold, and it is given to the heir who did not participate in the abortion (i.e., brother/sister or grandparent(s), etc., according to the laws of inheritance).
However, the only condition under which abortion is allowed is when there is an actual threat to the life of the mother confirmed by an official medical report that if the pregnancy advances any further, the mother may die.
Given the above, since the abortion was done in the case in hand before the fetus was 120 days old, then no compensation is liable. However, it remains a sin, which one should ask forgiveness for and promise never to commit again. If the mother wishes to give in charity besides all this, then that is even better. Allah Almighty says in the Qur'an: (Verily, the good deeds omit the bad deeds… ) (Yunus 10: 114)
Excerpted, with slight modifications, from: www.ecfr.org
Allah Almighty knows best.