A woman’s menstrual cycle can vary in length each month – it’s important for a woman to know her days of bleeding (hayd) and purity (tuhr) in case she has irregular bleeding (istihada). She will then have to look at her record, in order to align her bleeding with her place of menstruation and the number of days she regularly bleeds.
The Fiqh of It
If a woman experiences bleeding earlier than her normal place of habit, she cannot assume that it is hayd. Her place of habit is when she is due to bleed in relation to her recent hayd and tuhr habits. For a detailed explanation of the place of habit, refer to ‘Number & Place’.
There are three possible rulings that can apply to early blood: