After marital relations (sexual intercourse) you are in a state of ritual impurity (called Janabah where recitation of Qur’an is not allowed) which is different from the state of menstruation (haidh). During menstruation even though there is a difference of opinion you are allowed to recite Qur’an without touching it physically. Some scholars even encourage it.
A ritual bath (ghusl) is not necessary right away in the case that a lady’s menstrual period begins immediately after sexual intercourse. It must be noted that during her menses, the husband is not allowed to have intercourse in the vagina. Almighty Allah says:
And they ask you about menstruation. Say, “It is harm, so keep away from wives during menstruation. And do not approach them until they are pure. And when they have purified themselves, then come to them from where Allah has ordained for you. (Al-Baqarah 2:222)
Watch this short talk with Sheikh Abu Eesa to know about the rulings of menstruation.