Multi-phase combination-type sequential preparation for oral contraception and method of oral contraception

A multi-phase combination-type sequential preparation for oral contraception consisting of 20-22 tablets each containing a gestagen and an oestrogen characterized in that a first phase consists of 5-8 tablets, each of which contains a low dose of gestagen and a relatively high dose of oestrogen, a second phase of 5-8 tablets each having a gestagen dose which is greater than that during the first phase and an oestrogen dose which is smaller than that in the first phase, and a third phase of 5-11 tablets each of which has a gestagen dose equal to or greater than that during the second phase and an oestrogen dose equal to or less than that in the second phase, wherein the gestagen is selected from the group consisting of desogestrel and the 3-oxo derivative thereof, and the oestrogen is ethinyloestradiol, the amount of gestagen in the first phase tablet being less than or equal to 0.050 mg, the amount of oestrogen in said first phase tablet being less than 0.050 mg, the amount of gestagen in the three phases being in the ratio of 1:1.5-5:3-6.