Sex during Menstruation
By considering the discomfort of the women during the monthly periods, Islam has forbidden both the husband and the wife from sexual intercourse during the menstruation.
The Qur'an says, They ask you about menstruation. (O Muhammad) tell (them that) menstruation is a discomfort (for the women, it is a period when they pass through physical and emotional tension. Therefore,) do not establish sexual relations with them during the menses, and (again you are reminded that) do not approach them (sexually) until the blood stops. Then when they have cleansed themselves, you (are permitted to) go into them as Allah has commanded you (by placing sexual urge in your nature). (2:222)
Of course, playing with the other parts of her body (other than the vagina and anus) is allowed. Again, it is precautionarily better not to play with her body between the navel and knees.
If a man who is engaged in sexual intercourse with his wife discovers that her period has began, then he should immediately withdraw himself from her.
It is clear from the verse mentioned above (until the blood stops) that once the blood has stopped, intercourse becomes lawful even if the woman has not performed ghuslu 'l-hayz. But on the basis of the subsequent sentence (then when they have cleansed themselves...), most of the fuqaha' (Islamic jurists) have ruled that it is precautionarily better to refrain from intercourse until she performs ghusl or, at least, washes her private parts.
'Ali bin Yaqtin asked Imam Musa al-Kazim (peace be upon him) about a man having intercourse with his wife whose period has stopped but she has still not performed the ghusl. The Imam said, "There is no harm in it; but (intercourse) after the ghusl is more preferable to me.` 14
Notes:
14. Ibid, p. 573.
Adopted from the book : "The Ritual Ablutions for Women (Taharatu N-Nisa')" by : "Sayyid Muhammad Rizvi"