Praise be to Allah.
If the wife is sick and cannot bear the hardships of pregnancy, then it is permissible to abort the foetus within the first forty days of the pregnancy, according to the view of a number of scholars.
It says in a report issued by the Council of Senior Scholars:
1 – It is not permissible to abort pregnancy at various stages thereof, except for a shar’i reason, and within very narrow limits.
2 – If the pregnancy is in the first stage, which is the first forty days, and aborting it is for a legitimate shar’i purpose or to ward off harm, then it is permissible to abort it. As for aborting it at this stage for fear of hardship in raising children or for fear of not being able to afford the expenses of raising and educating them, or for fear of their future or because the couple is happy with the number of children they already have, that is not permissible.
3 – It is not permissible to abort a pregnancy if it is a ‘alaqah or mudghah (i.e., in the second and third forty-day periods of pregnancy) unless a committee of trustworthy doctors has determined that allowing it to continue will pose a danger to the safety of the mother because they fear that she will die if it continues. In that case it is permissible to abort it after trying all other means to avoid risk to the mother.
4 – After the third stage, and after four months of pregnancy have been completed, it is not permissible to abort it unless a number of trustworthy specialists have determined that leaving the foetus in his mother’s womb will cause her death, and after exhausting all means of trying to save his life. A concession allowing abortion subject to these conditions is only granted so as to ward off the greater of the two evils and achieve the greater of the two interests. End quote from al-Fataawa al-Jaami’ah (3/1056).
And Allaah knows best.