All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
A husband has the right to delay his wife's pregnancy for a fixed period of time if there is some interest in such an action.
So, his wife is highly advised to feel free to obey her husband in this concern. At the same time, the husband has to choose the easiest ways and the least harmful means. So, using condoms, for example, is more proper than uncovering the wife's Awrah (parts of body to be covered) or fixing a loop. The husband has to consult experts about this issue.
But, if the husband wants to use a means to delay his wife's pregnancy for fear of large number of children and their responsibilities, or for fear of poverty and so on, then he should not postpone his wife's pregnancy, since such thinking constitutes an evil thought about Allah, who warrants their sustenance. This also constitutes disagreement with the Prophetic Hadeeth: "Marry the woman who is affectionate and fertile, so I will be proud of your multitude in front of other nations." [Ahmad and Abu Daawood; Al-'Iraaqi regarded it as sound]
Anyway, if the husband persists in his stand, we advise the wife to be patient and gentle with him; perhaps he may regain his rationality.
We ask Allah to make all affairs of Muslims good in this worldly life and in the Hereafter.
As for permanent birth control, you may refer to Fatwa 83837.
Allah knows best.