I am pregnant with four twins since two months although I didn't have childbearing potential during the last four years. In addition, the doctor specialized in reprusccusions, already has notified me about the possible reprusccusions as a result of being pregnant with four twins as follows: abortion, Metrorrhagia, Premature birth, high blood pressure, gestational diabetes and the like. What is the ruling on aborting some of the aforementioned embryos? A medical report was attached in which the status of my question is clarified.

Is it permissible to offer Tahajjud prayer after Witr prayer?

It is permissible to offer voluntary prayer after Witr (An odd number prayer performed between Isha and Fajr) prayer. However, it is desirable that the night prayer be ended with Witr. Therefore, it is desirable for one, who thought that he was most probably going to wake up at night in order to offer Tahajjud, to offer Witr after it, but one, who fears that he might not wake up, should offer Witr before going to bed.

What is the ruling on making a false oath?

Making false oath indulges its maker in Hell; therefore, he is obliged to repent, ask Allah for forgiveness and make an expiation; feeding 10 poor or providing clothes for them and in case of incapability of doing any of latters he should fast for 3 consecutive days. And Allah Knows Best. 

I placed my hand on the Quran and made an oath to avoid doing a specific matter, but the devil seduced me. What is the ruling on this?

You are obliged to pay an expiation; feeding 10 poor and the cost of feeing one is half JD. And Allah Knows Best.