But Does it Work?


The million dollar question: Does NFP work?1

Well, yes, it does.

In hundreds and hundreds of real-life trials, involving literally millions of cycles, modern methods of NFP have been found again and again to be extremely effective for avoiding pregnancy when they are thoroughly learned and consistently used.

This bears repeating: Modern methods of NFP are extremely effective for avoiding pregnancy when they are thoroughly learned and consistently used.

Learning NFP means receiving formal instruction, either in person from a certified teacher or through a home-study course that includes having charts reviewed by an instructor or through an internet teaching service, in a particular method of NFP.

Using NFP means keeping an accurate, written chart, every day, and consistently following all of the guidelines, for one particular method, exactly as they are written.

There is nothing immoral about not keeping a written chart or combining aspects of multiple methods of NFP or following the guidelines for avoiding pregnancy only partially, but there is also no way of knowing whether this will allow the couple to reliably avoid pregnancy and when we talk about the studied effectiveness of NFP we are talking only about the effectiveness for couples who have learned and are using a specific, recognized method.

Consider the following quote from a study investigating the effectiveness of the Creighton Model of NFP:

“[T]he following net pregnancy probabilities were found per 100 couples: method-related pregnancies, 0.14; pregnancies caused by user and/or teacher error, 2.72; pregnancies caused by achieving-related behavior (genital contact during a time known to be fertile), 12.84”2

In less technical language, this study found that among couples who learn the Creighton Model from certified instructors for the purpose of avoiding pregnancy:

  • Fewer than 2 in 1000 will conceive despite correctly follow the guidelines for avoiding pregnancy.
  • Fewer than 3 in 100 will make a mistake in charting or interpreting that will result in pregnancy.
  • More than 1 in 10 will conceive as a result of consciously deciding not to follow the guidelines for avoiding pregnancy.

From a secular perspective the fact that approximately 15% of couples who start out intending to use NFP to avoid pregnancy nonetheless become pregnant is a problem and that the overwhelming majority of these couples conceive as a result of consciously deciding not to follow the guidelines to do what they set out to do (avoid conceiving) is not significant. The eyes of faith, however, see something quite different.

The practical and logistical aspects of NFP are not terribly burdensome. Learning is not expensive (some teachers charge nothing at all, most charge less than $200 for complete instruction and virtually all will be perfectly happy to waive fees in cases of financial hardship), takes no more than a handful of hours spread over a couple of months and can be accomplished without ever leaving your house.3 Charting requires less than a minute a day and is simple enough to have been mastered by women all over the world, including many who are illiterate. And when a couple finds themselves confused or unsure about how to interpret the woman’s chart, assistance from a trained teacher is only a phone call or email away.4

Nonetheless using NFP to avoid pregnancy is a commitment. Even aside from the fact that abstaining during times of possible fertility can be a struggle, it requires daily attention to observe, chart and interpret the signs of fertility. The use of NFP to avoid pregnancy is, in fact, a kind of regular fasting – an intentional giving up of something both very desirable and wholly good – and fasting clarifies.

The use of contraception has been compared to stuffing ear plugs into the ears of the soul. The world screams that we must Control Our Fertility and Plan Our Families. God, the still, small voice, whispers, “Be open now. Right now I long to bless you with a child – a child who will play an unrepeatable part in my eternal plan. Trust me.”

The commitment and self-sacrifice required to avoid pregnancy using NFP open the ears of the soul to God’s voice and test the strength of the couple’s conviction that now is not the time for another child. So it should not be surprising at all that some couples who begin using NFP with the intention of avoiding pregnancy find, after a time, that perhaps it is not so important after all. When both husband and wife remain certain that it is very important that they do not conceive, couples usually do not find NFP overwhelmingly difficult and when a couple does find that NFP is becoming increasingly burdensome (despite seeking help from a certified teacher if the charts are confusing) it may well be because it is time to reconsider whether there are really still serious reasons to avoid pregnancy. Sometimes continuing to use NFP to avoid pregnancy is a burden simply because the need for it has passed.

1. Sometimes the claim is made that the primary purpose of NFP is to discern whether or not it is God’s will for the couple to have another child and therefore it always works since whatever happens can be understood as being God’s will. There is truth to this, but I also think it is a somewhat evasive answer to a serious question: Can couples who are already certain that they must avoid pregnancy trust NFP to allow them to do so?

2.”Pregnancy probabilities during use of the Creighton model of FertilityCareTM System” Howard, M.P.; Stanford, Joseph B. Archives of Family Medicine Vol.8, Number 5. Month/Quarter: September/, 1999. Page(s)391-402

This particular study is just one of many which have found approximately the same results for a number of different modern methods of NFP. For other studies on the effectiveness of the Database of NFP Research available at One More Soul (www.omsoul.com) is an unbeatable resource.

3. The Billings Method of NFP can be learned entirely from home via the Internet Teaching Service available at www.woomb.org and the Symto-Thermal Method can be learned through the Couple to Couple League’s Home Study Course available at www.ccli.org.

4. Both of the above sites, as well as www.fertilitycare.org (Creighton Model) and www.omsoul.com (all methods), include directories of NFP teachers who are available to answer questions, review confusing charts and provide refresher courses. Be aware, though, that because all of these organizations work on very tight budgets and almost all NFP teachers are volunteers, some of the directory entries may be out-of-date and you may need to call or email a couple of different teachers before actually making contact.

For additional “cyber-support” you are also most welcome to join in the discussions in the Catholic Mom Community’s NFP Forum

Looking for more information on Natural Family Planning?  Visit our Natural Family Planning Resource Center.


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  1. Pingback: MePregnant

  2. I have some strong desire to eat sour fruits. My favorite so far is grapefruit. I hope this wont last throughout my entire pregnancy.

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