It is haraam to have sexual intercourse knowingly while menstruating. The Qur'an says Allah has majide, ويسألونك عن المحيض قل هو أذى فاعتزلوا النساء في المحيض ولا تقربوهن حتى يطهرن فإذا تطهرن فأتوهن من حيث أمركم الله إن الله يحب التوابين ويحب المتطهرين and ask tomara menstruation (periods) about. Tell me , it is unclean. Therefore, abstain from sexual intercourse during menstruation. Do not approach them until they have become pure. When you have purified yourselves , go to them as Allah has commanded you. Surely Allah loves those who turn to Him in repentance and those who guard (against evil). (Surah Al-Baqarah: leave) hadith, عن أبي هريرة, عن النبي صلى الله عليه وسلم قال "من أتى حائضا أو امرأة في دبرها أو كاهنا فقد كفر بما أنزل على محمد صلى الله عليه وسلم Abu Huraira rayi. It is narrated that the Prophet ( peace and blessings of Allaah be upon him) said : Whoever has intercourse with a menstruating woman or has intercourse with her in the vagina or goes to the fortune teller, he disbelieves in what has been revealed to Muhammad ( the Qur'aan). (Jame Tirmidhi 13 Ibn Majah 639) So first of all you should repent and seek forgiveness from Allah. Moreover, it has been narrated in some hadiths that if you have sexual intercourse at the beginning of menstruation, you should give one dinar and at the end of it, half a dinar. Therefore, in this case, along with repentance and apology, it would be better to give charity according to the above rules. It is revealed that the dinar is a gold coin. Which is the equivalent of 4.364 grams of gold at present. (Jame Tirmidhi , Hadith 138 ; Musnad Ahmad , Hadith 2201 ; Baylul Majhud 2/26 ; Albahroor Rayek 1/196 ; Fathul Qadir 1/146 ; Fatawal Walwalizia 1/56 ; Addurrul Mukhtar 1/296)