Does NFP Really Work?
This week is NFP Awareness week. NFP advocates are proudly spreading the word that NFP is a highly effective method of family planning.
Unfortunately, the rest of the world doesn’t doesn’t think that NFP and fertility awareness based methods of family planning are so effective. While “perfect use” effectiveness is quite high, “typical use” effectiveness is significantly lower.
Note: For purposes of this post, “fertility awareness” refers to the method alone, while NFP refers to the method taught in the context of Catholic teaching. In other words, NFP is simply a specific way of using fertility awareness.
Scientifically, using any form of fertility awareness requires some work. Partners must learn their fertility, chart their observations, correctly interpret the chart, and follow the rules. This is, admittedly, more work than a set-it-and-forget-it method, like an IUD.
Still, people aren’t afraid to work for their health. How much effort do people put into eating right and exercising? How much time to people spend counting calories, buying local food, working out, or sports training? Compared to this, fertility charting is something very healthy for very little effort.
Nor is charting difficult for most women. With proper instruction, over 90% of women can identify their Peak day on the first cycle. Only a small number of women have problems with using the method, many of which can be resolved with more advanced hormone monitoring, improved diet, or medical intervention.
Fertility Awareness Users Are Different From the General Population
But why is the user method failure rate so high? Why do couples who rely on fertility awareness for family planning seem to have so many children?
One possible explanation of the high user failure rate is Simpson’s Paradox. Simpson’s Paradox is a phenomenon in statistics where when you lump data from unlike circumstances together, trends can disappear and even reverse.
A classic example is batting averages (with a nod to blogger Iowahawk). Imagine two batters, Hitter A and Hitter B.
– Against right-handed pitchers: 300 at-bats, 90 hits (.300 average)
— Against left-handed pitchers: 200 at-bats, 50 hits (.250 average)
Total: 500 at-bats, 140 hits (.280 average)
– Against right-handed pitchers: 100 at-bats, 32 hits (.320 average)
— Against left-handed pitchers: 300 at-bats, 78 hits (.260 average)
Total: 400 at-bats, 110 hits (.275 average)
Hitter B has a higher batting average against both righties and lefties, but Hitter A has a higher overall average. A closer look at the numbers shows that the only reason why Hitter A had the higher average is because he faced more right handed pitchers, against whom both A and B had a better batting average. Hitter B is the better hitter.
What does this have to do with fertility awareness?
Not all couples use fertility awareness based methods. Couples who used fertility awareness based methods for family planning are usually in stable relationships and are disproportionately devoutly Catholic and married.
Think about it: What couples would have the most difficulty with any method of family planning?
- Couples in a committed relationship.
- Couples who enjoy frequent sex. (More opportunities for conception.)
- Couples who don’t have a strong motivation to avoid pregnancy.
- Couples who have an intercourse-focused sexuality.
- Couples who have objections to supplementary methods of pregnancy prevention (i.e. barrier methods).
- Couples who are ambivalent toward family planning.
- Couples dealing with demanding life events, such as having a new baby.
Hmmm, sounds like a lot of happily married, “open to life”, devout Catholic NFP couples, doesn’t it?
Effectiveness Depends on Motivation
With fertility awareness based methods, when couples are OK with becoming pregnant, they tend to start taking chances with the method, and eventually they become pregnant. That’s a big reason why we, and many other couples are “bad at NFP”. We’re simply not motivated to avoid pregnancy enough to actually follow all the rules.
The Catholic Church considers this not to be a bug, but a feature of NFP—because the Catholic Church teaches that babies are good, that married couples should be open to life, and that couples should have good reasons not to avoid pregnancy.
But if a someone does have serious reasons for not becoming pregnant, then what?
In China, the government’s brutal One Child Policy gives ALL users a high motivation for not becoming pregnant. A recent study of the Billings Ovulation Method in China found a user-effectiveness rate of 99.5% with ZERO method related pregnancies. While it is likely the couples used the method very conservatively, fertility education allowed them to safely avoid pregnancy more effectively and more safely than the “highly effective” Copper IUD.
Anecdotally, couples with a very serious reason to avoid pregnancy DO use the method very cautiously. Some will feel like their need to avoid pregnancy is so serious that they do need to completely abstain from intercourse. (This is more common among unmarried women.) Because the methods give women and couples an awareness of their fertility, they can adjust the methods to meet their needs by being more conservative. You can’t do that with a Pill.
While women who have difficulty with the method are generally excluded from most studies, this number is low. According to BillingsLife, 90% of women are able to identify fertility on the first cycle with the Billings Method, with only 10% requiring additional help, while another study from Dr. Richard Fehring at Marquette University found that method problems affected only 7% of couples. As research and technology advances, I expect this number to drop.
The other reason for the low user effectiveness rate is the wide variety of quality of instruction. We have taken three different classes and read the classic Taking Charge of Your Fertility. Different instructors take different approaches, some of which are more effective than others.
Good instruction allows a woman to understand how her body works and how to recognize her own pattern of fertility. Good instruction will teach men to notice the changes in their partners throughout the month. Instruction that is primarily rule-based, primarily ideological or religious in content, or inaccurate or outdated, will not give couples the information they need to be able to effectively use the method.
Poor teaching is a solvable problem. Just like Wikipedia has given the world access to a better encyclopedia than could even be imagined 15 years ago, technology will allow the best practices and best methods to come to the forefront. When it was difficult to find any information, bad information was rampant. As information becomes more available, what is good and what is bad will become more apparent. Online classes will make the best methods accessible to everyone, not just those near a teacher.
Confirmation Bias and Religious Prejudice
But looking at the data, the problem is not so much that “NFP doesn’t work” as it is a matter of confirmation bias. People make of their minds about fertility awareness based methods and they pay attention to the data that agrees with their position. It’s why people remember “NFP surprises”, but forget all the “Pill babies” out there, even though the real-world pregnancy rates are about the same.
Often the bias is rooted in a distrust or dislike of the Catholic Church:
- “Everybody knows” NFP is the rhythm method.
- “Everybody knows” the rhythm method doesn’t work.
- “Everybody knows” that’s why the Catholic Church wants couples to use it—to make more Catholics.
- “Everybody knows” the Catholic Church hates women.
- “Everybody knows” the Catholic Church hates sex.
- “Everybody knows” the Catholic Church hates science. (Galileo! Galileo!)
- “Everybody knows” the Catholic Church wants nothing more that to make married couples miserable.
Recently, Real Clear Science editor Ross Pomeroy decided to study “Catholic birth control”. To his surprise, it was scientific and effective.
To me, [the Catholic argument against contraception] 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.
Pomeroy is no fan of the Catholic Church, but he acknowledges that despite his views of Catholic theology, fertility awareness based methods are indeed effective.
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.
This is why even though most users are highly satisfied with NFP/FAM, the negative stories get the most attention. Looking closer at the negative experiences, only 7% of couples have a negative experience due to the method, with the rest struggling due to relational or spiritual issues.
Fertility awareness based method require cooperation between the couple. No matter how the couple uses the method, each partner must sacrifice his or her desires (at some level) for the good of each other. If a couple has relational problems, then the method is going to bring them to the surface. Often the “problems with NFP” are a sign of broader sexual problems or are a sign that the couple may be using sex to cover up other problems in the relationship.
If a couple is using the method for religious reasons and they have a negative or unhealthy view of God and spirituality, then of course they are going to be miserable. This is common with “strict Catholics” who believe in a God that wants them to suffer and is waiting to send them to hell for any infraction. (This is not actual Catholic theology, by the way.) If you believe that God (or the Catholic Church) wants you to be miserable, then you’re not going to be surprised when following “God’s laws” makes you miserable. But having an axe to grind against God, the Catholic Church, or countless individual Catholics, is not a problem with the method. The problem is spiritual, therefore the solution is to gain a healthier, more positive, spirituality. (I write about this frequently at realcatholicloveandsex.com.)
Conventional Wisdom is About Fertility Awareness is Wrong
The conventional wisdom in the secular world is that fertility awareness based methods are best for married couples who can afford to make a mistake with the method because the user failure rate is high. The reality is that the user failure rate is high because couples who chose to use such methods are often the ones who are least motivated to avoid pregnancy.
The conventional wisdom among some in the Catholic world is that teaching people who are not married or preparing for marriage these methods encourages people to use the method to engage in non-marital sex. The reality is that when young women learn about their bodies, they often make better decisions about sex. Knowing how her body works can tell women when it’s love and when it’s just hormones. (Plus, it’s good medical information.)
The conventional wisdom is that fertility awareness is difficult to learn and that not every woman can know her own body. But as long-time fertility awareness and women’s health advocate Laura Wershler tweeted:
Thinking women can’t learn how to chart their menstrual cycles, is like thinking girls can’t learn to read. Thinking women w/problem periods can’t learn
#fertilityawareness is like thinking those with dyslexia can’t learn to read. Not teaching girls and women the signs of fertility and how their menstrual cycles work contributes to unintended pregnancies. Teaching girls & women signs of fertility & how their cycles work would decrease unintended pregnancies.
It’s also important for the guys too. Knowing what my wife’s body is doing allows me to better respond to her and to better understand her. This understanding has allowed me to be a better husband and a better lover.
Fertility awareness empowers women and empowering women empowers men. It is knowledge that every woman should have about her body (and something guys should know a bit about too.)