Answer:
(Fatwa: 77/77=M=1431)
It is mustahab to perform ghusl between two subsequent intercourses. If one had intercourse without having bath and his wife was conceived, the baby shall be legitimate, but doing so is not better.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
