This is not a yes or no answer, as you may have suspected. It’s really about HOW MUCH you can rely on your birth control method. We’ve been discussing how effective different methods are over one year of use, but you may be wondering what to expect after 2, 5 and even 10 years of using the same method. Keep in mind that people tend to hop between methods or have gaps in using birth control when they want to get pregnant or for other reasons.
Using the same numbers for effectiveness in one year for their calculations, Gregor Aisch and Bill Marsh created an interactive tool to show the likelihood of failure (an unintended pregnancy). This tool was published in their article in the New York Times last week. You can hover over any time point between 1 and 10 years to see the number of pregnancies expected among 100 women.
Now go play with the tool! They have included 15 different birth control methods in their interactive tool. Here’s a screenshot of how a few of the charts looks when I hover over the 10 year mark on the X-axis (I added the horrified and happy faces for dramatic effect):
The bolded number in the top-left represents the number of women who will have an unplanned pregnancy after typical use of that method of birth control, in this case for 10 years. The solid line reflects typical use and the dashed line is perfect use. If you need to refresh yourself on the difference between perfect and typical use, review this previous post.
Of course this tool does not take into consideration a few realities:
- Women who are not using their method correctly and consistently will either become pregnant or switch methods.
- Women who are using their method correctly and consistently will likely continue to use the method for a longer duration.
- Women who use their selected method for a longer duration will take it more correctly and consistently over time as they become more experienced with the method.