The Pill: Four Basic Types
The constant-dose combination pill has been available since the early 1960s and is the most commonly used oral contraceptive in the United States. It contains two hormones, synthetic estrogen and progestin (a progesterone-like substance). The dosage of these hormones remains constant throughout the menstrual cycle. There are more than 32 different varieties of combination pills, and each variety contains various amounts and ratios of the two hormones. The amount of estrogen in pills has decreased from as much as 175 micrograms in 1960 to an average of 25 micrograms (Ritter, 2003).
At a Glance
■ TABLE 10.3 Remember "ACHES" for the Pill: Symptoms of Possible Serious Problems With the Birth Control Pill
*The risk of nonfatal blood clots among users of birth control pills containing drospireone is greater than that of pills containing levonorgestrel (FDA, 2011). SOURCE: adapted from Hatcher & Guillebaud (1998).
The triphasic pill, which has been on the market since 1984, is another type of oral contraceptive. Unlike the constant-dose combination pill, the triphasic pill provides fluctuations of estrogen and progestin levels during the menstrual cycle. The triphasic pill is designed to reduce the total hormone dosage and any side effects while maintaining contraceptive effectiveness.
Another constant-dose pill on the market is called an extended-cycle contraceptive because it is taken continuously for 3 months without placebo pills. The only brand on the market, Seasonale, has a lower dose of estrogen and progestin than most other constant-dose or triphasic pills. Seasonale reduces the number of menstrual periods to 4 instead of 13 per year, which significantly benefits women who have uncomfortable menstrual symptoms during the placebo phase of using the combination pill (Kripke, 2006).
The progestin-only pill, which has been on the market since 1973, contains only 0.35 milligrams of progestin—about one third the amount in an average-strength combination pill. Like the combination pill, the progestin-only pill has a constant-dose formula. The progestin-only pill contains no estrogen and is a good option for women who prefer or require a non-estrogen pill (Burkett & Hewitt, 2005).