Question: I have a medical illness, and have become pregnant recently, under what circumstances is an abortion allowed?
Answer: Abortion is not allowed after the implantation of the [fertilized] ovum [on the lining of the womb], except if the mother’s life is in danger, and in this case, it would be permissible to abort the foetus as long as the soul has not entered into it (i.e. before the end of 4 months); after the entering of the soul, it is not permissible, as an obligatory precaution.
Ayatollah Al-Sayyid Ali Al-Husseini Al-Sistani