A woman didn’t pray because she miscarried and was bleeding. However, the loss of the fetus happened before 80 days. She didn’t pray because she didn’t know she was supposed to. Does she have to make up these missed days?

That blood is not nifas, it is istihadah, because the fetus is not formed before eighty days. She prays in that state, and the prayers she left should be made up. Imam Ibn Baz was asked about a miscarriage under two months and said the prayers she left, she should make them up.