Types of Birth Control Pills
More than 45 years since the U.S. Food and Drug Administration (FDA) approved "the pill" in 1960, it continues to be the most popular and one of the most effective forms of reversible birth control. Today, American women have more than 40 different oral contraceptive products from which to choose.
"The pill" is the common name for oral contraception. There are two basic types of birth control pills: combination pills and progestin-only pills. Both are made of hormones like those made by a woman's ovaries. Combination pills contain estrogen and progestin. Both types require a medical evaluation and prescription. Both can prevent pregnancy.
Progestin-Only Pills (mini-pills)
The progestin-only pills (also called "mini-pills") became available in the 1970s. Their use was and has been limited - making up only one to 10% of contraceptive market. This type of pills contains no estrogen. Estrogen-free pills are ideal for breastfeeding women because estrogen reduces milk production. Progestin-only pills are also ideal for women with health conditions that preclude use of combined oral contraceptive pills, such as migraine (vascular) headaches, thromboembolism, and cardiovascular disease.
In addition, progestin-only pills do not have most of the estrogen-related side effects of oral contraception: nausea, headaches and other symptoms associated with starting the combined pill are minimal. However, bleeding and spotting days during the intramenstrual period may be higher than with the combined pills and missed pills may result in a higher chance of pregnancy that with the combined oral contraceptives.
These pills primarily work by thickening the cervical mucus, thereby preventing sperm from entering the uterus. The minipills do not usually prevent ovulation because they don't contain estrogen. To work effectively, they must be taken at a certain time every 24 hours. Even missing one pill can greatly reduce effectiveness.
When you hear the term "birth control pill," it most often refers to oral contraceptives containing estrogen and progestin. Combination pills contain a combination of these two hormones. They are categorized as monophasic, biphasic, or triphasic pills depending on whether the level of hormones stays the same during the first three weeks of the menstrual cycle or changes.
Combined birth control pills work by preventing ovulation (the release of a mature egg from a woman's ovary). Combined pills thin the endometrium (the lining of the uterus). The hormones also cause the cervical mucus (liquid at the opening of the uterus) to thicken, which can stop sperm from getting into the uterus.
Monophasic pills have a constant dose of both estrogen and progestin in each of the hormonally active pills throughout the entire cycle (21 days of ingesting active pills). Several of the brands listed above may be available in several strengths of estrogen or progesterone, from which doctors choose according to a woman’s individual needs. Because of the uniform hormone level in all the pills, monophasics are least likely to cause side effects, such as mood changes, that can result from fluctuating hormone levels in the body.
The U.S. Food and Drug Administration approved a new packaging of a monophasic birth-control pill called Seasonale in 2003. The product is packaged in a 91-day supply and is designed to prevent menstruation for the entire time period. Women taking Seasonale will have only four periods a year. Seasonale contains the same estrogen (ethinyl estradiol) and progestin (levonorgestrel) in the same amount as many other monophasic birth control pills. Although many other monophasic birth control pills are used in this way, Seasonale is the only product approved for use.
Phasic pills were developed in the 1980s. Multiphasic oral contraceptives contain varied amounts of hormones and are designed to be taken at specific times throughout the entire pill-taking schedule. They were developed to reduce side effects of oral contraceptives, including breakthrough bleeding, spotting and amenorrhea, associated with higher levels of hormones.
Biphasic pills change the level of progestin hormones once during the menstrual cycle. The progesterone dose is increased about halfway through the cycle.
Triphasic pills contain three different doses of progestin hormones in the active pills (changing every seven days during the first three weeks of pills). Triphasic pills gradually increase the dose of estrogen and some pills also increase the progesterone dose.
Quadriphasic pills have been developed to reduce the side effects of oral contraceptives and are presented as more physiological since they mimic the natural cycle. However, quadriphasic oral contraceptives may have increased risk of pill-taking errors caused by the array of different color pills, complicated directions for catching up when a pill is missed, and the higher price.
Emergency contraceptive pills (ECP)
Emergency contraceptive pills are not intended to be used regularly as a contraceptive. They are designed to prevent pregnancy after unprotected sex (when standard contraceptives fail or no method was used). The FDA has approved one emergency contraception pill called Plan B, which contains the progestin levonorgestrel.
Advantages of ECP: reduces the chance of unintended pregnancy, can be obtained easily - Plan B will soon be available over the counter for women 18 and over can be obtained in advance and kept handy in case of an emergency such as condom breakage, missed oral contraceptives, late contraceptive injections or forced sex.
Disadvantages: timing, because you must take the first dose within 120 hour of having unprotected sex. The sooner you take them after unprotected intercourse, the more effective they are. That's why it's a good idea to have a prescription or a supply of emergency contraceptive pills available should the need arise.
Extended-cycle pills prevent pregnancy and allow you to have a period only every three months. Lybrel stops the periods for a year.
Which Pill is better?
Monophasic birth control pills work as well as the more expensive and more complicated biphasic and triphasic products. Monophasic products with low amounts of estrogen may cause less bloating or breast tenderness but more breakthrough bleeding. So for most women, the monophasic birth control pills represent a good first option. All combination products containing both estrogen and progestin are more effective in preventing pregnancy than are the "mini-pills." However, progestin-only pills are a good choice for breastfeeding women and for women who can't use combined oral contraceptives pills.
References & Resources
Published: May 05, 2007