There’s a lot of misinformation about family planning out there, but the one method with the worst PR has got to be “Natural” Family Planning, more neutrally known as Periodic Abstinence. You know the joke, right? What do you call someone using the Rhythm method? Mommy! Unintended pregnancy is hilarious, and only happens to rubes! But the truth is that periodic abstinence can be a useful tool in planning or avoiding pregnancy, and it’s a great choice for some female-bodied people and their partners. In fact there are lots of people whose cultural, religious or health situations make it the only acceptable choice. Not to mention it’s free (perhaps you were unaware that other forms of birth control may be unaffordable in this economy). If only periodic abstinence could get loose from the people who keep trying to push this one method on everyone else.
First, we need to review how contraceptive effectiveness is described. When someone throws around the statistic that such and such a method is 90% effective, you might think that meant that one time out of ten that you have sex, the method is going to fail, but I am happy to explain that that is incorrect. 90% effectiveness means that if 100 couples (a term I will use henceforth to mean couples capable of creating a pregnancy) use a given contraceptive method exclusively, on average 10 of them will have an unplanned pregnancy by the end of one year. A 90% effectiveness rate could also be reported as a 10% failure rate. The implied comparison is to couples taking no measures to affect their fertility; doing nothing is associated with 15% effectiveness (or 85% failure) at preventing pregnancy.
Furthermore, each method should have two numbers describing its effectiveness, the “perfect use” effectiveness, and the “typical use” effectiveness. Perfect use means something different for each method. For oral contraceptives it means taking the pill every day at the same time, for diaphragms it means correct insertion technique, etc. As you might conclude, the perfect use number will be more optimistic than the typical use. There is a school of thought that since basically no one uses contraceptives perfectly, perfect use numbers are misleading and should not be reported. Reporting typical use only would actually be more consistent with the drug and device trials are usually analyzed. Any source that tries to skip over typical use, or doesn’t specify which type of effectiveness they are reporting, should not be trusted.
Let’s look at some numbers from the Guttmacher Institute. You will immediately notice that there is more than one method of periodic abstinence. The rhythm method, or calendar method, is what most people associate with natural family planning, but several techniques are available for pinpointing the fertile days of a woman’s menstrual cycle more accurately, including ovulation test kits that detect hormone levels in urine, taking body temperatures and getting familiar with how your cervical mucus changes over the course of the month. Another conclusion that should jump out from this table is that periodic abstinence is not a waste of time. Remember that doing nothing has a failure rate of 85%. Typical use of periodic abstinence has a failure rate of 25%. That is roughly the difference between a pregnancy every year and a pregnancy every four years. Clinicians who fail to inform themselves about this option are missing an opportunity to offer their patients a powerful method of controlling their fertility.
A third interesting finding is that periodic abstinence has the largest difference between perfect use and typical use. The perfect use failure rates for the symptothermal or ovulation methods are about the same as the rates for condoms (by which I mean “male” condoms, the kind you’re used to). That makes periodic abstinence a great choice for people who have relatively few barriers to adherence–women with a lot of control over their reproductive lives, who are motivated to make this method work, who have access to training in the more sophisticated techniques for tracking fertility, and who have the ability to keep good records of their cycles. Obviously the male partner also has to cooperate with abstaining from sex during fertile periods. That makes this method a more realistic choice for, say, a mutually trusting couple in a stable relationship than it does for, say, a domestic abuser and his victim, or a sex worker and her clients.
As a public health measure, however, periodic abstinence has quite limited utility. Really, when it comes to large population approaches, nothing beats condoms. Condoms have real drawbacks when it comes to user satisfaction (there is a reason why free rubbers remain less popular than free beer), but they are cheap, easy to use and…oh yeah, they also offer protection against STIs. Churchill-style, we might say that they are the very worst form of contraception except for all the others. But it might be useful to think of the two methods as being useful to very different populations. Even if great strides were made and periodic abstinence became more practical and more popular, it would never be the best choice for everyone. No method is, because there is infinite variation in people’s sexuality and reproductive health.
Proponents of Natural Family Planning could be much more effective if they could uncouple themselves from the anti-condom agenda. Amanda Marcotte at Double X was quite right to be steamed about a group from Georgetown claiming that their new gizmo for tracking fertility was more effective than condoms by comparing perfect use of the one to typical use of the other (now you, too, know what’s wrong with that reasoning). It’s unfortunate that it is so difficult to have a rational conversation about what should be just another family planning option with its own specific costs and benefits.
So how do we make sure that the women for whom periodic abstinence might be a life-changing option can get objective information from people who are not trying to dictate the terms of their sexuality? One option is for members of the religious and socially conservative communities to embrace and support the diversity of sexual experience, and to offer good and complete information about condoms and the full range of contraceptive choices. The other is for the medical and reproductive rights communities to make sure periodic abstinence gets fair play. Let’s see who gets there first.
P.S. Just a reminder that you’re not limited to just one form of birth control. If a backup method works well for you, go ahead and hedge your bets. No method has a 0% failure rate, not even surgical sterilization. Along those lines, one application of fertility tracking is that couples who do not want to abstain during the fertile period can use barrier methods those days instead, without having to worry about them the rest of the month.
ETA (2/26/2016): In response to a reader comment below, I have changed some of the original language of this post. It formerly referred to “straight couples” rather than couples capable of creating a pregnancy. I also changed some language about “women” to language about female-bodied people.