A study to be published in the Journal of Family Planning & Reproductive Health Care says that the standard days method of natural family planning, using "beads" to tell you when you're fertile, is more than 95 percent effective in avoiding pregnancy. The claim is that it's more effective than a condom.
Here are some reasons to take that with a gigantic grain of salt: It's not an equal comparison, because condoms can be used on any day, whereas the whole point of natural family planning is not having intercourse on days you're fertile. (According to Guttmacher, the failure rate for condoms in the first twelve months of "perfect use" is 2 percent, and 17.5 percent for "typical use.) UPI says it's in the October issue of the Journal (not that we can find), doesn't say if the 95 percent number is among typical use or perfect use. It tracked 1659 women in three countries over three years.
Natural family planning is popular in Catholic circles, for whom avoiding sex on fertile days to avert conception is preferable to using hormonal or barrier methods to avert conception. Victoria Jennings, a professor at the Catholic Georgetown University Medical Center Institute for Reproductive Health, who conducted the study also happens to be the one who developed the beads. They sell for about $27 and there's also a smartphone app.