Still, despite agreement between 60 of the 64 theologians and nine of the fifteen cardinals on the commission that the ban on contraception should be lifted, Pope Paul VI decided to retain it.
Couples "are not free to act as they choose in the service of transmitting life," he wrote. Instead, Catholics are to seek "the will of God and remember . . . that each and every marital act must of necessity retain its intrinsic relationship to the procreation of human life."
Today, this policy still applies to the world's 1.2 billion Catholics, yet many of them freely flout it. According to the Guttmacher Institute, 83% of Catholics use male or female sterilization, intrauterine devices, the pill, or condoms in order to avoid unwanted pregnancy.
Little known and rarely utilized is the single method of birth control supported by the Catholic Church. Righteously termed "natural family planning," the method limits sexual intercourse to women's naturally infertile periods, such as certain portions of the menstrual cycle, menopause, or during pregnancy. Pope Paul VI's rationale for approving natural family planning versus other methods was that it "uses a faculty given by nature whereas contraception impedes nature."
To me, that seems a dogmatic and unscientific argument. So I assumed that the method itself would be similarly lacking in evidence. But to my surprise, I was wrong.
As it's typically used, natural family planning is about as effective as the female condom -- between 75 and 80% successful at preventing pregnancy over the course of a year. But when perfectly used, it can be 95% effective or higher. A large study conducted in 2007 found that the "symptothermal" method of natural family planning, in which the female user tracks both her body temperature and cervical secretions to gauge her fertility, is 99.6% effective when properly adopted, roughly the same as a copper intrauterine device.
Natural family planning has drawbacks, of course. It does not prevent sexually transmitted diseases and it also restricts sexual activity to select times. These two factors likely contribute to the method's small following in the United States, where only one to three percent of women use it.
But beyond its mere use as a tool to stymie "artificial" contraception in the First World, natural family planning has potential humanitarian applications in the Third World. In the 1990s, the World Health Organization worked with 869 women from a multitude of diverse ethnic and socioeconomic backgrounds and found that 93% of them could be trained to identify the symptoms distinguishing fertile and infertile periods of the menstrual cycle. In 1993, R.E.J. Ryder commented in the British Medical Journal, "It might be argued that natural family planning, being cheap, effective, without side effects, and potentially particularly effective and acceptable in areas of poverty, may be the family planning method of choice for the Third World."
The Catholic Church's official stance condemning contraception is, in my view, dubious and disempowering to women. But though dogmatic religious leaders may deny the overt benefits of contraception, an open mind cannot deny based on the available evidence that their lone alternative is indeed effective.