Everyone has heard horror stories about a condom breaking or a woman getting pregnant despite being on the pill. While no method of contraception offers a 100 percent guarantee, familiarity with the reasons why birth control fails, and knowing how to choose the method that matches your needs, can help couples keep their risk of unplanned pregnancy low.
Does It Work?
While about half of all pregnancies in the United States are unintended, the Centers for Disease Control and Prevention's National Survey of Family Growth found that more than 90 percent of women between 15 and 44 use contraception. When choosing a form of contraception, most women's very first question is: "How well does it work?"
A method of contraception's efficacy depends, primarily, upon how consistently and properly it is used. Certain surgical procedures and device methods—such as female sterilization, vasectomy and intrauterine devices (IUDs)—lend themselves to perfect use and fewer unintended pregnancies because once these procedures are performed, nothing more is required of the user. But what about the other types of birth control?
"The main source of contraceptive failure comes from those methods that require adhering to some schedule, such as birth control pills or condoms," says James Trussell, PhD, director of the office of population research at Princeton University and the author of review on contraceptive failure published in the journal Contraception in August. "The main reason they fail is not that they are used and fail, but because of imperfect use."
"Methods like condoms, cervical caps, diaphragms and spermicides, must be used every single time you have sex," he continues. And things happen, condoms break and microscopic holes form in diaphragms, compromising the barrier between sperm and the vagina. But the most common mistake people make is not using any method at all. "The way these are most often misused is that they are in the bathroom cabinet or in the drawer next to the bed rather than in the vagina or on the penis," he says. Likewise, women taking oral contraceptives may forget to take their pill.
How well a contraceptive methods works must be weighed in terms of perfect and typical use. This is the difference between following the method's directions by the book and using it inconsistently and incorrectly. According to Dr. Trussell's review, when using the male condom for example, 16 percent of women experienced an unintended pregnancy over the course of one year with typical use and 6 percent got pregnant with perfect use.
So What's Right for You?
Of course, just because sterilization provides very effective protection, that doesn't mean it's the appropriate choice for you, especially if you plan to get pregnant in the future. Consequently, your age may play a major role in that decision. Age may also affect what kind of contraception you can afford and which contraception best fits into your lifestyle and level of sexual activity.
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Another consideration is protection against sexually transmitted disease, which is one reason why Dr. Trussell and others advocate using two methods of contraception. "A dual method strategy where one uses condoms and birth control pill, for example, would provide not only extremely effective contraception protection but also protection against sexually transmitted diseases," says Dr. Trussell.
It you're deciding whether to go on oral contraceptives, you should consider how good a pill taker you are, or whether you've had success with this method in the past. If you have trouble remembering to take the pill each day, you might consider the patch, which has a sticky side that you attach to a part of the body and change weekly, or the ring, which is a device that is inserted into the vagina.
Health status and sensitivity to side effects are other considerations. If you are already at high risk for stroke, for example, oral contraceptives might not be a good choice. However, oral contraceptives might be ideal if you have acne or severe PMS or perimenopause symptoms. Likewise, contraceptives such as diaphragms and spermicides can increase risk of urinary tract infections, particularly among those who are already prone to them, but are nonetheless favored by many women over 30.
"The cardinal rule of contraceptive is that a woman or a couple needs to find a method that they can use correctly and consistently," Trussell says. "We have a variety of contraceptives, and choice is good, because it increases the likelihood that an individual woman or couple can find the methods that is best for them."
| Percentage of Women with an Unintended Pregnancy During the First Year of Typical Use and the First Year of Perfect Use of Contraception * | ||
|---|---|---|
| Method | Typical Use | Perfect Use |
| Male sterilization | 0.15 | 0.10 |
| Female sterilization | 0.5 | 0.5 |
| IUD: Copper T | 0.8 | 0.6 |
| IUD: levonorgesterel-containing intrauterine system | 0.1 | 0.1 |
| Depo-Provera | 3 | 0.3 |
| NuvaRing | 8 | 0.3 |
| Ortho-Evra patch | 8 | 0.3 |
| Combined pill and mini-pill | 8 | 0.3 |
| Male condom | 15 | 2 |
| Diaphragm | 16 | 6 |
| Withdrawal | 27 | 4 |
| Spermicides | 29 | 18 |
| No method | 85 | 85 |
* Adapted from Trussell, J. Contraceptive Technology, eighteenth edition revised. Ardent Media, 2004.
