All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
We have already issued Fataawa 87304 and 85197 clarifying that it is not permissible to resort to permanent birth control except for a dire necessity.
However, it appears –Allaah Knows best –that the existence of this physically challenged child is not a sound reason that allows you to resort to permanent birth control. Moreover, one may resort to permanent birth control and one day he may feel the necessity of having more children, so you should be careful about this.
Nonetheless, it is permissible to resort to a temporary birth control for a need as we clarified in Fatwa 84436. This is something which you may consider if necessary. For more benefit, please refer to Fataawa 117945 and 84468.
Allaah Knows best.