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 ask Allaah to exalt his mention as well as that of his family and all his companions.
We have already issued Fatwa 83269 clarifying the ruling on a woman who prays in trousers. Of course the ruling applies to whether the trousers are loose or not. Even if a woman wears trousers that do not shape the 'Awrah (parts of the body that must be covered in Islam) she is nevertheless not free from resembling men. If in wearing trousers she imitates men, then according to the Hanbali school she is obliged to make up her prayer, as they stated that whoever performs the prayer wearing forbidden clothes, must make it up unless he did not know that this is forbidden or forgot. However, other scholars are of the view that her prayer is correct and she is not obliged to make it up.
Allaah Knows best.