"Menstruation is like replacing the bedsheet (I just thought about this today ha so just bear with me a little). A woman's body starts to make a bed of blood inside her womb. Then, about a week later (after the old bedsheet has been removed/menstruation), a veil of cervical mucus is sent out (4-5 fertile days) so that the groom (sperm) will be protected from the harsh acidic environment. "