Hello,
There are 24 active tablets in a pack of loestrin and 4 iron pills.
You get bleeding during those 4 days when you are using iron pills.
If you want to postpone your periods then after finishing 24 tablets,don't consume those 4 iron pills and straightaway start taking the new pack.
Once you stop taking these active pills you shall get breakthrough bleeding or periods.
If during the use of pills,there is a heavy spotting,nothing is to be done as it shall become all right of its own.
Thanks

loestrin should be started on first day of menstrual cycle (first day of bleeding), take one blue tablet daily at the same time each day without skipping for 24 days followed by one white tab for 2 days then one brown tab containing iron for 2 days. During these last two-three days bleeding (withdrawl bleeding) occurs. After end of 28 tabs start new pack without any gap. you have to stick to this schedule to avoid pregnancy. You can take as long as you want to avoid pregnancy. If you stop it abruptly, in between the cycle, withdrawl bleeding will occur. There are side effects associated with OCPs such as nausea, headache, weight gain, braest tenderness, vaginal dischage, some serious side effects like DVT, stroke, MI etc though incidence is less as compared to high dose estrogen pills