Sheikh Mohamed El-Moctar El-Shinqiti, Director of the Islamic Center of South Plains,Lubbock, Texas, states: “There is difference between intending to make I`tikaf and making nadhr (vow) to do I`tikaf. If the woman intends to make I`tikaf in the last 10 days of Ramadan and then she was later interrupted by labour, then she does not have to make up for the missed days of I`tikaf. However, if she makes a nadhr to do I`tikaf in the last 10 days, then she has to make up for the days she missed.
having said this, I just want to remind everyone that fasting is a prerequisite for I`tikaf, while the pregnant woman does not have to fast. Therefore, if you make a nadhr to do I`tikaf, then you have to fast as well.