Do you know how this pills act and how your menstrual cycle works?
There are mainly 4 Hormones which comes into act-
During a normal cycle this 4 maintain a perfect balance.
First few days the Oestrogen maintain the endometrium but during the mid cycle there is sudden rise in FSH and LH which causes Ovulation. Then again oestrogen takes the control and progesteron also play a role. Then the level decrases and endometrium can not maintain itself thus menstruation
Now when you using this throughout the cycle you are suplementing oestrogen and progesterone from outside thus no LH & FSH surge- no ovulation. After 21st day the rest 7 tablets are nothing but iron tablets , so during this time no hormonal
support from outside so similar situation arises like menstruation endometrium can not maintain itself. These occurs due to withdrawl of hormonal support thus this is called WITHDRAWL BLEEDING.
Hope you understand,
Have a good health.