Chapter 154 – Regulations Concerning the Menses
154.1) Regular time of menses is determined by three consecutive times.
154.2) Most women calculate the time by days between cycles.
154.3) Some women find it difficult to predict. Three consecutive acts may be considered menses regulated by physical symptoms. (See source for details, or consult a rabbi.)
154.4) Some women calculate the regular days by both intervening days and physical symptoms.
154.5) A woman with a regular period is presumed to be clean at all times, except during her menstrual period.
154.6) A woman who is not regular should examine herself before and after intercourse to ascertain her cleanliness.
154.7) If a woman is uncertain of her menstrual cleanliness, she should stay away from her husband during times of uncertainty.