Are there differences among birth control pills?
Birth control pills can differ not only in the number of active ingredients, but also in the way ingredients are dosed: Monophasic birth control pills contain the same amount of ingredient in each active pill. Multiphasic birth control pills contain varying levels of hormones through the month. They were designed to minimize side effects such as breakthrough bleeding, which is bleeding that occurs between menstrual periods. Low-dose oral contraceptives contain less estrogen than other types of birth control pills. They contain 20 micrograms of estrogen, compared to 30 to 50 in other birth control pills.
