What is the difference between monophasic, biphasic and triphasic combined oral contraceptives?Updated a year ago

All monophasic, biphasic and triphasic combination oral contraceptives have estrogen and progestin in each daily dose. 

However monophasic pills have a fixed dose of estrogen and progestins in each pill pack. 

Biphasic and triphasic combinations are designed to deliver estrogen and progestins in varying doses to try to minimize the total hormone dose that you will get. 

Biphasic combinations will have a fixed amount of estrogen, however they have 2 different concentrations of progestins for each week of your cycle. 

Triphasic combinations usually have a fixed dose of estrogen, then 3 different concentrations of progestins for each week of your cycle. These kind of combinations may be used to minimize adverse side effects that may come with  oral contraceptive use.