Q & A with Dr. Cullins: Birth Control
I am getting married and have been doing a lot of research on birth control. My church has introduced me to natural family planning — the Creighton model. I like everything about it, but my only hesitation is its effectiveness. I can't seem to find any "negative" statistics on this method and all the websites seem biased. It is very important for me and my future husband that I do not become pregnant, and I am very wary about the effectiveness of NFP. What are your thoughts on this method?
Certainly, a high level of contraceptive effectiveness is critical for couples for whom it is very important to avoid unintended pregnancy. The most authoritative source we know for comparing the effectiveness of various methods of birth control is Contraceptive Technology, by Robert H. Hatcher et al., which is published by Ardent Media. The most recent edition became available in 2004. You can order it online or consult a copy in the reference section of your local library.
Contraceptive effectiveness is the rate of success of the use of a birth control method in the first year. It is calculated in two ways: typical use and perfect use. Typical use is the rate of effectiveness for couples who use a method incorrectly or inconsistently some of the time in the course of a year. Perfect use means that couples use a method correctly and consistently all the time over the course of a year. For example, of 100 women who rely on latex condoms for contraception, 15 will become pregnant in one year of typical use, but only two will become pregnant in one year of perfect use. So, for latex condoms, the typical-use effectiveness is 85 percent, while the perfect-use effectiveness is 98 percent. Sometimes we use the rates for typical and perfect use to express a range of effectiveness. In this example, the range for the condom would be 85-98 percent
Fertility awareness-based methods, which some people refer to as "natural family planning," are not as effective as some other methods, especially with typical use. For example, the ovulation, or mucus method, on which the Billings and Creighton models are based, ranges from 78-95 percent effectiveness. The symptothermal method, which combines the mucus method with the basal body temperature method, ranges from 80-98 percent. The new Standard Days method, which uses a string of colored beads with a movable marker to track the days of a cycle, is 88-95 percent effective.
According to Contraceptive Technology, the most effective reversible contraceptives — those that are not meant to be permanent — are the IUD (intrauterine device) and the hormonal methods — the pill, the patch, the ring, and the shot. The effectiveness of the IUD ranges from 99.2-99.9 percent. The effectiveness of the pill, the patch, and the ring ranges from 92-99.7 percent. And the effectiveness of the shot ranges from 97-99.7 percent.
Effectiveness, however, is only one of the considerations a woman needs to think about to decide what option will work best for her. To decide which method to use, you may want to consider how each method will work in eight other ways as well:
- How well will it fit into your lifestyle?
- How convenient will it be?
- How safe will it be?
- How affordable will it be?
- How reversible will it be?
- Will it help prevent sexually transmitted infections?
- How important is it for you to prevent pregnancy?
- How long do you want to prevent pregnancy?
While any contraceptive is better than none, the choice of method makes a difference. And studies have shown that women who use the method they most prefer are more likely to prevent pregnancy because they are more likely to continue using their method.
Published: 05.18.06 | Updated: 10.02.07
This column is for informational purposes only and is not intended to constitute medical advice, diagnosis, or treatment. If you have a medical problem, please call toll-free 1-800-230-PLAN for an appointment with the Planned Parenthood health center nearest you.