Scientific Studies Proving that NFP works?

I don’t know much about science, and I know that moral law against contraception does not depend on the efficacy of NFP.

But I’m on another board where people want scientific proof that NFP works.

I found this research article below.

But they responded that:

*"No control group. (So nothing to compare it to, to make sure that there are no other factors that influence the result)
Small sample (only 229 by the end of the study!)
Short period (1 year - many people who want to, take longer than that to conceive!)

Something just generally smells: According to this study, the conception rate for people who made no effort to avoid pregnancy at all is only 7.5%. Which means they could, with the same amount of certainty, have stated that taking no precaution at all is more effective (92.5%) at avoiding pregnancy than the male condom, which, IIRC, is about 80-90% effective. This clearly fails this “Does this make logical sense?” test. (I would guess this is due to the short period of the study and biased subject selection.)*

Any help?

Try reading this website for starters–it is posted by Marquette University and also has references for their research at the bottom.

By “works” I assume you mean low failure rates?

To anyone here who is very knowledgable about NFP, what do you say about the following?

The reported failure rates for modern NFP methods range from less than 1 to 5 percent for perfect use, and 2 to 25 percent for typical use.16,1930 The few randomized controlled trials of NFP methods have been limited by poor recruitment and high dropout rates.31 Therefore, the evidence for NFP methods is based on observational trials that are prone to selection bias.

I think after that was written, another randomised clinical trial’s results may have come out. EHFM I think stands for “electronic hormonal fertility monitor” and CMM for “cervical mucus monitoring”

The net correct use efficacy of both the EHFM and CMM group is very good, i.e., 98- 100% survival rate (or a 0 – 2 pregnancy rate per 100 women over 12 months of use) and compares with what is found in the literature (Trussell 2004; Trussell 2010). As hypothesized, the monitor group has better total pregnancy rates than the mucus group, i.e., a 7% unintended pregnancy rate among the monitor group versus 18% among the mucus group. The differences in pregnancy rates between the monitor and mucus group are similar to the differences that were found in a previous cohort comparison study of the monitor plus mucus versus mucus alone as two methods of NFP (Fehring, et al, 2009). The low unintended pregnancy rate (both perfect and total) are comparable to the pregnancy rates that were determined in a large European study that used mucus plus basal body temperature as a double check for the beginning and end of the fertile phase of the menstrual cycle (Frank-Herrmann et al. 2007) and with a pilot cohort study of the online FABM conducted by the authors of this study, i.e., a 9% pregnancy rate among ovulating, non-breastfeeding participants (Fehring, et al., 2011).

Here is a review of this study:

Other studies:

A study by the World Health Organization involving 869 fertile women from Australia, India, Ireland, the Philippines, and El Salvador found that 93% could accurately interpret their body’s signals regardless of education and culture.2] In a 36-month study of 5,752 women, the method was 99.86% effective.47]


The Standard Days method was developed and proven by the researchers at the Institute for Reproductive Health of Georgetown University. CycleBeads, unaffiliated with religious teachings, is a visual tool based on the Standard Days method. According to the Institute of Reproductive Health, when used as birth control, CB has a 95% effectiveness rating. Computer programs are available to help track fertility on a calendar.48]

This may be the study that is discussed here from 2002:

Natural Family Planning Method As Effective As Contraceptive Pill, New Research Finds

This came out in 1998:

DALLAS—The Creighton method of natural family planning (NFP) is roughly as effective as the birth control pill when used to avoid pregnancy, according to a 14-year, five-state study published this summer in a U.S. medical journal.
The study, which appeared in the June issue of the Journal of Reproductive Medicine, distributed to obstetrician-gynecologists, showed the method to have a 99.5% rate for method effectiveness, that is, when it is taught and used precisely, and a 96.8% use effectiveness rate, a “real-life” rate that includes teaching or use errors.

Read more:

The beauty of NFP is that it also works effectively for couples trying to conceive. I would like to see studies on that aspect as well.

Thank you Abyssinia and Ophelia,

Are any of the studies scientifically controlled? If not, why not? Thanks, Pat

Any help?

If you read the article you posted they attempt to answer his objection below.

“For the risk taking couples who had unprotected intercourse during the fertile time, the pregnancy rate increases up to 7.5% per year. **We acknowledge that this is surprisingly low. **However, one has to realize that the median fertile time determined by the STM is 13 days a cycle (less days after the first year). The potential fertile time is in fact longer than the actual physiological fertile time. Therefore, we recognize that some of the couples were practising conscious intelligent risk taking, i.e. no unprotected intercourse during the few highly fertile days and intercourse only occurred on days at the margins of the beginning and end of the fertile time that would be considered to be a relatively low fertile time.”

It’s not a very diverse group of women that are being studied but rather a group of mostly Catholic women (75%) who may have a desire to prove the effectiveness of NFP.

Presumably this is a controlled study because two groups using two different methods are looked at? Am I wrong?

Review of this study:

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