Beware of researchers with hidden religious agendas: That is the lesson behind research proclaiming that the rhythm method is more effective than condom use. At first blush, it's exciting to read reports that Cycle Beads—which unsurprisingly look like rosary beads, but are supposed to help you track your ovulation to avoid pregnancy with huge bouts of sexual abstinence—are more effective than condoms. But a little closer look should give readers a reason to be skeptical, and to demand more research from uninterested third parties, as well as research that follows the standard protocol for reporting on effectiveness rates of contraception methods.
There are two big red flags in this research. First of all, the research was conducted* by the Institute for Reproductive Health out of Georgetown, a group with an overt Catholic anti-contraception agenda. They put most of their effort into pushing people around the world away from pills and condoms and toward the "fertility awareness method," which is a fancy new term for the rhythm method. (When there are constant new names for the same old concept, that should also be a red flag for quackery.) They are so dedicated to this Catholic anti-contraception mission that they also invest in fighting HIV by doing anything but promoting and distributing condom use, even though condoms have been shown to be highly effective at preventing the transmission of the virus.*
All this would be less important if the study seemed rigorous, but it simply seems to be more propagandistic than scientific. Not a single one i found referencing this study made mention of the standard ways of measuring contraception effectiveness rates. When you're discussing rigorous researched effectiveness rates for a method, you divide the users into two categories: typical users (people who use a method inconsistently) and perfect users. Not a single report on this research mentions typical vs. perfect users. The problem with this is the anti-choice movement has a tendency to cite only perfect use numbers when describing their preferred contraception methods, abstinence and periodic abstinence called by various names (fertility awareness, natural family planning, rhythm method), but they cite the typical use methods for the contraception they disdain. For instance, you'll frequently see anti-choicers say abstinence is 100 percent effective while claiming the pill has a 9 percent failure rate, but what they fail to mention is that they're comparing perfect-use abstainers to typical-use pill users. Since 82 percent of teenagers who claim to use abstinence as their primary form of contraception actually fail to use the method, and 85 percent of them who don't use a back-up method will get pregnant within a year, we can safely say abstinence has abysmal typical-use rates. The reports on the study, which hasn't been published yet, suggests that was their tactic: eliminate all women who had sex during the fertile periods (i.e. used the method imperfectly) and then compare the massaged numbers to the typical use effectiveness rates of condom users. Perfect use for condoms results in a 98 percent effectiveness rate.
The reason I suspect this is that periodic abstinence requires a lot of abstaining, which is why the Junior Anti-Sex League likes it second best to complete abstinence. The rule of thumb is that the less sex you're having, the better in their eyes. Cycle Beads certainly display this anti-sex agenda; the method requires abstaining from days 8-19 of your cycle, meaning 12 full days a month, meaning the Cycle Beads method indicates five more days of abstinence than is suggested by non-religious, pro-choice sources who teach fertility awareness. As many couples prefer not to have sex on a woman's period, the Cycle Beads method leaves you less than half a month open for having sex. For most couples who are still strongly into having sex with each other, that's simply unacceptable. Experts in comprehensive sexual health care will generally tell you that the more a method leans on deprivation and hostility to sexual pleasure, the less likely it is that women will stick with it for the long haul, making all variations of the Catholic-endorsed rhythm method highly unlikely to be an adequate substitute for condoms or hormonal methods.
Corrections, October 14, 2011: The original version of this post said that the Institute for Reproductive Health funded the Cycle Bead research. The research was funded by the U.S. Agency for International Development. The original version of this post also posited that the Institute for Reproductive Health makes and sells the Cycle Beads. It does not.