7 2 1 rule for menstruation is a tool used to identify or detect any abnormal bleeding during the periods. It is called as menorrhagia (heavy menstrual bleeding). It helps to identify abnormal uterine bleeding (AUB).
What exactly 7 2 1 means?
The numbers are as,
7 – You should notice that, if bleeding occurs for more than 7 day
2 – You need to change the pad every 2 hours because it get soaked
1 – Blood clots that pass through bleed is similar or more than 1 inch
Click here to read :- Menstrual Cycle Phases
So if you notice any abnormality then consult the gynecologist immediately.