Suppress ovulation. Birth control pills work by suppressing ovulation. The estrogen it it regulates periods. They also increase a protein called sex hormone binding globulin which binds extra sex steroids and can decrease acne. Some rare side effects include blood clots in legs. It is best to give a new pill three months to get used to it.
If I have a breakthrough period should I be worried about my birth control's effectiveness at preventing pregnancy?
BTB. If you are taking birth control pills every day, break through bleeding can occur. Break through bleeding has nothing to do with the effectiveness of the birth control pill.
Started birth control (microgestin) on 2nd day of period, how long till it is effective in preventing pregnancy?
This month. As long as you take the pill everyday as directed at the same time each day, the pill is effective this month. Some exercise caution by using a "back up" method of contraception for the first month in conjunction with the pill.
Birth control pills aren't making my periods lighter, does that mean it is not working properly in preventing pregnancy? Been on pills for 4 months
NO. The pills are designed to hormonally control your cycle and prevent pregnancy. They are not designed to make periods lighter.