NFP: 99% Effective?

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seanflynn

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When people give me a statistic, like “NFP is 99% effective,” or 98%, 99.5%, 92.1% or whatever, do they mean “Only one percent of presumed-infertile marital embraces causes pregnancy” or “only one percent of couples perfectly practicing NFP ever have an unnplanned pregnancy?”

The first option I gave there means many more unplannd pregnancies than the second.
 
The effectiveness of NFP (or any family planning method) is quoted in terms of a percent. What ‘99% effective’ means is that if 100 couples were using that method according to the guidelines for avoiding pregnancy for one year, you could expect that one pregnancy would occur.

Recent trials of modern NFP methods (eg. Billings, Creighton, symptothermal) show greater than 99% effectiveness at postponing pregnancy. However, that means that a couple is following the rules of that method (ie. receiving instruction from an accredited instructor, keeping an accurate daily chart, abstaining from all genital contact on days of potential fertility as identified by the rules of the method).

For pretty much all family planning methods (including NFP, hormonal contraception, barrier methods etc.) the pregnancy rate of ‘typical use’ is higher than the pregnancy rate for ‘perfect use’.
 
The pamphlet at my doctor’s office says that 1 in 4 women will become pregnant while using NFP. Of course, I’m sure there is human error involved as the poster above stated and that this does not apply to the perfect use of all NFP methods together.
 
seanflynn said:
When people give me a statistic, like “NFP is 99% effective,” or 98%, 99.5%, 92.1% or whatever, do they mean “Only one percent of presumed-infertile marital embraces causes pregnancy” or “only one percent of couples perfectly practicing NFP ever have an unnplanned pregnancy?”

The first option I gave there means many more unplannd pregnancies than the second.
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What I’m pretty sure it means is that “only one percent of couples perfectly practicing NFP ever have an unnplanned pregnancy?”

However the accuracy rating is waaay lower then 92.1%. It is not a very accurate form of birth control but if you want to use that then by all means go ahead. Just figure you will most likely get pregnant before you want.
 
“The lead author of the report, Petra Frank-Herrmann, assistant professor and managing director of the natural fertility section in the Department of Gynaecological Endocrinology at the University of Heidelberg, Germany, said: “For a contraceptive method to be rated as highly efficient as the hormonal pill, there should be less than one pregnancy per 100 women per year when the method is used correctly. The pregnancy rate for women who used the STM method correctly in our study was 0.4%*, which can be interpreted as one pregnancy occurring per 250 women per year*. Therefore, we maintain that the effectiveness of STM is comparable to the effectiveness of modern contraceptive methods such as oral contraceptives, and is an effective and acceptable method of family planning.””

European Society for Human Reproduction and Embryology (2007, February 21). Natural Family Planning Method As Effective As Contraceptive Pill, New Research Finds. ScienceDaily. Retrieved September 23, 2010, from sciencedaily.com* /releases/2007/02/070221065200.htm
 
The pamphlet at my doctor’s office says that 1 in 4 women will become pregnant while using NFP. Of course, I’m sure there is human error involved as the poster above stated and that this does not apply to the perfect use of all NFP methods together.
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As a doctor in training, I’ve always wondered about this too. Most of the information on NFP I’ve seen (such as in textbooks, package inserts for OCPs, etc) gives the effectiveness of NFP as 75%, meaning (as another poster has stated) that out of every 100 couples using NFP to avoid conception, by the end of a year, 25 of those couples would have “failed” and wound up with a pregnancy. I have not seen the higher numbers anywhere except on NFP websites, which you could argue have a motivation to overestimate effectiveness. Well, ok, other than the link PaulinVA has put up. And yes, before anyone points it out, I’m sure someone writing a package insert for OCPs has motivation to underestimate the effectiveness of the “competition”.

But even allowing for bias, there is a vast difference between 75% and 99%. Why the discrepancy? Now, I’m thinking that maybe the 75% stat is based on the old “rhythm method” which was just based on a calendar and wouldn’t work for women who didn’t have regular cycles. Unfortunately, many non-Catholics still think that is all NFP is, and have no idea there are more sophisticated methods available now. But considering how many posts I have seen here by people who lament the many Catholic families with only 1-2 kids, apparently assuming such families MUST be using ABC, it seems many Catholics also assume NFP isn’t that effective, they just don’t mind because to them the idea of NFP is to just reduce the number of children to a manageable level (say, 4-5 instead of 9-10).
 
Toe, in my experience, yes, the charts at the OB’s office generally lump all forms of NFP in together, i.e., rhythm is in with the more sophisticated methods practiced today. Do not underestimate the motivation of the drug companies to denigrate NFP; IIRC, the OCP scrip is the most prescribed scrip in the country, literally billions of dollars. What financial interest does CCL have in comparison to that? If you check Merck or other OCP manufacturer’s websites, there will often be a link to the statistic, and it will show what methods are included.

I often cite Petra Frank-Herrman work too, and as far as I know she is a secular researcher.

As far as your speculation about Catholic motivations for using NFP, I think the best you could say is that it is just that, speculation. I am not aware of anyone IRL or online who has ever espoused the attitude you describe, only 4-5 instead of 9-10 by using NFP.

The Catholic Church teaches that couples are to practice responsible parenthood. The couple is to prayerfully discern what God is calling them to at a particular moment in time, what their responsibilities to the other spouse are, what their responsibilities to the existing family are, and what their responsibilities to society are. If the couple discerns that they have a serious reason to postpone pregnancy, they can totally abstain or practice NFP, moral means to accomplish the legitmate goals of responsible parenthood.
 
You’re looking at a biological function that can be impacted by a myriad of issues as well as the human failure to follow all directions. I’d be surprised if NFP can give consistent success rates about 80-85% especially if you factor in those who are infertile and unaware of it.
 
Perhaps you should call Petra Frank-Herrman and tell her that her research is wrong, lutheranteach.

Have you ever practiced a method of fertility awareness?

There are lots of studies besides the ones PaulinVA and I are referencing.

If you are going to give credit to infertility in NFP’s case, don’t you have to assume the same for all the other methods? Won’t that be a wash?
 
I didn’t mean to speculate on the reasons why a particular couple would use NFP, and I haven’t actually heard any particular person say they are just using NFP to cut down on the total number of children from 9-10 to 4-5. It seems that couples using NFP are supposed to use every cycle as a chance to discern whether they should try to avoid or not, so it’s not like starting out marriage thinking “I definitely only want four kids” or whatever.

However, I have seen different estimates of the practical effectiveness of NFP, even from reading this forum. I say practical, as different from the method effectiveness, which was what was discussed in Frank-Herman’s work, the effectiveness expected if people were perfect at the method, However, obviously people are not perfect, and I think much of the debate is really about how effective NFP is in “real life”, not in a highly controlled research study. It seems there are people here who agree with the Church’s teachings but don’t think much of NFP as an effective method of avoiding conception. Again, some posters here seem to assume that any long-married couple with “only” 1-2 kids MUST be using ABC, not NFP. Maybe that’s just because it’s statistically more likely, but it seems that there is an underlying assumption that if a couple was using NFP they’d wind up with more kids than 1-2 because NFP is just not that effective. Now, I know some posters here have successfully used NFP to avoid for years and have very serious, even life-and-death reasons for doing so. But I’ve also seen posts by people who mention having not just one, but two or even more children conceived while using NFP.

Now, I also understand that the effectiveness of NFP really doesn’t matter when discussing when it is moral to use it. I’ve seen some stats that indicate that condoms are less effective than NFP in avoiding, but I know that doesn’t make condom use more moral than NFP. Neither, really, do the purpoted “side benefits” such as couples becoming closer spiritually, very low divorce rates among NFP users, etc. So perhaps all this discussion doesn’t really matter.
 
ToeInTheWater said:
As a doctor in training, I’ve always wondered about this too. Most of the information on NFP I’ve seen (such as in textbooks, package inserts for OCPs, etc) gives the effectiveness of NFP as 75%, meaning (as another poster has stated) that out of every 100 couples using NFP to avoid conception, by the end of a year, 25 of those couples would have “failed” and wound up with a pregnancy. I have not seen the higher numbers anywhere except on NFP websites, which you could argue have a motivation to overestimate effectiveness. Well, ok, other than the link PaulinVA has put up. And yes, before anyone points it out, I’m sure someone writing a package insert for OCPs has motivation to underestimate the effectiveness of the “competition”.

But even allowing for bias, there is a vast difference between 75% and 99%. Why the discrepancy? Now, I’m thinking that maybe the 75% stat is based on the old “rhythm method” which was just based on a calendar and wouldn’t work for women who didn’t have regular cycles. Unfortunately, many non-Catholics still think that is all NFP is, and have no idea there are more sophisticated methods available now. But considering how many posts I have seen here by people who lament the many Catholic families with only 1-2 kids, apparently assuming such families MUST be using ABC, it seems many Catholics also assume NFP isn’t that effective, they just don’t mind because to them the idea of NFP is to just reduce the number of children to a manageable level (say, 4-5 instead of 9-10).
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I’d say its the difference between the method effectiveness and the user effectiveness. Creighton is able to get its user effectiveness up because if you do engage in the act when your chart says you’re fertile, you’re automatically placed in the category of trying to conceive. Only in the first presentation were we given the statistic of the percentage of people switching their usage of the system. The other method’s however take a user effectiveness much more like how contraceptive user effective rates are studied. Its about the intention. So if a couple is not intending to get pregnant but is intimate when their chart says their fertile and then they get pregnant, that goes toward the user effectiveness.

As such, most NFP sources give you the studied method effectiveness and not the user effectiveness at all which can include more than knowingly using your fertile days, but can include inconsistantly charting, charting errors or using the method in a manner that doesn’t strictly follow the rules of the method.

I’d say overall, how well the couple uses the method depends on how well the woman understands her cycle and knows really what she’s doing when she’s charting. There is so much valuable info there beyond just trying to avoid or acheive pregnancy. I think charting well before a woman gets married is really benefitial. I think getting a crash course after you’ve already been married and active has to have some effect on how well the method is used. Besides, I think its good to see charting as health information and not merely as a family planning method. Its good to know overall what’s going on with your body. I don’t see the need to keep our cycles utter mysteries to us unless we have a need to know more simply for the sake of family planning.
 
ToeInTheWater said:
As a doctor in training, I’ve always wondered about this too. Most of the information on NFP I’ve seen (such as in textbooks, package inserts for OCPs, etc) gives the effectiveness of NFP as 75%, meaning (as another poster has stated) that out of every 100 couples using NFP to avoid conception, by the end of a year, 25 of those couples would have “failed” and wound up with a pregnancy. I have not seen the higher numbers anywhere except on NFP websites, which you could argue have a motivation to overestimate effectiveness. Well, ok, other than the link PaulinVA has put up. And yes, before anyone points it out, I’m sure someone writing a package insert for OCPs has motivation to underestimate the effectiveness of the “competition”.

But even allowing for bias, there is a vast difference between 75% and 99%. Why the discrepancy? Now, I’m thinking that maybe the 75% stat is based on the old “rhythm method” which was just based on a calendar and wouldn’t work for women who didn’t have regular cycles. Unfortunately, many non-Catholics still think that is all NFP is, and have no idea there are more sophisticated methods available now. But considering how many posts I have seen here by people who lament the many Catholic families with only 1-2 kids, apparently assuming such families MUST be using ABC, it seems many Catholics also assume NFP isn’t that effective, they just don’t mind because to them the idea of NFP is to just reduce the number of children to a manageable level (say, 4-5 instead of 9-10).
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If you would like some statistics on NFP from a source that is not pro-NFP, check out what Merck has to say about NFP effectiveness:

*The 1-yr pregnancy rates with of any of these methods is 25% with typical use. With perfect use, rates are 9% for the calendar method, 2% for the temperature method, 3% with the mucus method, and 2% with the symptothermal method. The symptothermal method is considered the most effective method of periodic abstinence because achieving perfect use is easier. *

merck.com/mmpe/sec18/ch255/ch255b.html

It’s interesting to note that the actual use pregnancy rates for oral contraceptives is about 8% and for barrier methods about 15 to 18%, which would mean that they are hardly bullet-proof. The nice thing about NFP is that the degree of efficacy is much more in the hands of the couple, and leads to increased levels of knowledge and communication.
 
Lutheranteach said:
You’re looking at a biological function that can be impacted by a myriad of issues as well as the human failure to follow all directions. I’d be surprised if NFP can give consistent success rates about 80-85% especially if you factor in those who are infertile and unaware of it.
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My wife and I have been using the STM for 20 years. It’s effective to conceive and to avoid.

Yes, people do have trouble, at times, applying the rules. But, overall, people are using NFP effectively.
 
When looking at effectiveness numbers (for example in a public health pamphlet comparing effectiveness of various methods) look at the basis for their numbers (there should be footnotes).

An NFP effectiveness rate of about 75% seems like this was based on anyone who self-describes as using NFP. This would include:
-people using the rhythm method
-people who are self-taught in NFP, or combining a number of guidelines in their own ‘system’ but not following a particular method
-people who are not charting consistently or accurately
-people who are occasionally or frequently having intercourse on days of known potential fertility
-couples who are generally wanting to postpone pregnancy, but may be somewhat ambivalent or undecided.
-people combining barrier methods with NFP

When you look at actual studies done of NFP applied according to the guidelines by couples (even illiterate, uneducated couples) who have been taught by a qualified instructor, the method effectiveness rates are at or above 99%.

Also, these methods are not, as one poster described, for just reducing the number of births from 9-10 per family down to 4 or 5. The Billings Method (a mucus-only method) has been widely used in China to enable couples to successfully adhere to the country’s (albeit unjust) one-child policy. If the couple is motivated to make it work, and has received proper instruction, they can make it work.

Finally, modern methods of NFP work for women in any situation of reproductive life, including normal cycles, irregular cycles, breastfeeding/postpartum, menopause, or disruptions to the normal pattern due to illness/hormonal imbalance (eg. PCOS, endometriosis, stress, etc.) They are not based on predicting when a woman might be fertile, but observing on any given day whether she is infertile that day or potentially fertile. That can be done even if she’s not having regular cycles.

I can also speak from experience. After 10 years of marriage, we have zero ‘surprise’ pregnancies. (4 deliberate ones).
 
Toe: the Frank-Herrmann user effectiveness was 98.2% (1.8 unintended pregnancies per 100 women per 13 cycles) - - it is in the next to last paragraph in PaulinVA’s link.

dulci - - there is no link that I saw on the Merck site breaking down what methods are included in the periodic abstinence figures. Does the periodic abstinence figure include those who are self-taught with no instructor backup? Does it include withdrawal, calendar rhythm, etc.? It looks like the Guttmacher/PP chart which I think is based on some research by Trussell, but I’m not sure one can tell from the site. Again, Merck is trying to sell you something. Is Frank-Herrmann? I am not saying Merck is being purposefully deceptive, but I do not think it is motivated to provide the clearest, most accurate numbers either.
 
twoangels said:
Creighton is able to get its user effectiveness up because if you do engage in the act when your chart says you’re fertile, you’re automatically placed in the category of trying to conceive. Only in the first presentation were we given the statistic of the percentage of people switching their usage of the system. The other method’s however take a user effectiveness much more like how contraceptive user effective rates are studied. Its about the intention. So if a couple is not intending to get pregnant but is intimate when their chart says their fertile and then they get pregnant, that goes toward the user effectiveness.
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I’ve never used Creighton…but any time my husband and I have changed our minds mid-cycle, I’ve ALWAYS considered that cycle to be TTC. Mainly because I figure…I KNOW we decided that it didn’t matter we were fertile and we engaged in intercourse anyway…so apparently we were NOT trying to avoid. 😃
 
Thanks for all the responses, people.

The impetus for my question was a conversation I had with a practicing Catholic friend of mine who said she needs to use birth control when she gets married because her anti-depressants (which I will stipulate are absolutely necessary for her, along with her other therapies) cause an incredibly high risk for severe birth defects if she becomes pregnant.

So what I was getting at, is that NFP is just as reliable as any pill, given perfect use. I assume someone with as much compassion on her potential children as to not want them to suffer from various diseases would be dedicated to the perfect use of an NFP method.

Anyway, I didn’t tell her my first reaction because I know how cold it sounds. It goes something like, “theologically or morally speaking, giving birth to a ‘defected’ child is certainly not evil. Knowing that a child will die very soon after birth may be painful for the parents, but will this child not go to heaven? It has comitted no personal sin, so just baptize him immediately and trust God. Contraception is still intrinsically evil. The Church is not ‘out of touch’ with your specific condition, you have a serious reason to avoid pregnancy and are therefore justified in delaying pregnancy indefinitely if need be, but only through the licit means of complete abstinence or natural family planning.”

Does anyone have a better way of saying this, or had to have this conversation before in real life?

Now, to respond to something else that came up:
Maybe that’s just because it’s statistically more likely, but it seems that there is an underlying assumption that if a couple was using NFP they’d wind up with more kids than 1-2 because NFP is just not that effective.
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I think the assumption is not that NFP is ineffective, so therefore couples with few kids can’t have practiced it exclusively. The general assumption I make is that if a couple takes seriously the Church’s teaching on marriage and contraception, then they will practice NFP and also be open to life. That is, they will intentionally have at least as many children as they think they can handle, maybe more than that if they make it a point to trust in God’s providence.

However, I hope I would not make assumptions about the fertility of other couples just looking at their number of children. They could have had multiple miscarriages, one partner could have become permanently infertile, or the practice NFP because they’ve discerned they have a serious reason to do so, even if I can’t figure out what that reason is.
[/Now, I also understand that the effectiveness of NFP really doesn’t matter when discussing when it is moral to use it. I’ve seen some stats that indicate that condoms are less effective than NFP in avoiding, but I know that doesn’t make condom use more moral than NFP. Neither, really, do the purpoted “side benefits” such as couples becoming closer spiritually, very low divorce rates among NFP users, etc. So perhaps all this discussion doesn’t really matter. QUOTE]
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It matters to me. 😛
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