What is the ruling of Islamic law regarding marital intimacy with one's wife during her menstrual period, and are there any medical or physical harms to the spouses as a result?

Intercourse with a menstruating woman in the vagina is among the great forbidden acts according to the Qur’an, Sunnah, and scholarly consensus. Allah the Almighty said: "And they ask you about menstruation. Say, 'It is a discomfort, so keep away from women during menstruation. And do not approach them until they are pure.'" The Prophet (peace be upon him) said: "Whoever has intercourse with a menstruating woman, or with a woman in her anus, or with a diviner and believes him, has disbelieved in what was revealed to Muhammad (peace be upon him)." Whoever believes that intercourse with a menstruating woman in her vagina is permissible has committed an act of disbelief. However, if one does so out of forgetfulness or ignorance, there is no sin upon them and no expiation is required. As for one who does so intentionally, knowing of her menstruation and the prohibition, and by choice, they have committed a grave sin and repentance is obligatory upon them. There is no expiation required of them, according to the more sound opinion.