Natural Family Planning: Average Length of Abstinence Required to Avoid Pregnancy

Yet another post about things I tell my sisters… about Natural Family Planning (NFP) and abstinence. 

.  .  .

This may be difficult for you to believe, but at some point you are likely to encounter people who are even more of the NFP cheerleader type than I am. You will hear them talk not only about the tremendous benefits of NFP, but also toss around stats.

Even pretty charts hint that reality can be complex

They will refer to the great blessings that come from the “week” of abstinence each month. They will be entirely sincere, and most likely speaking from personal experience.


Then thank God for your mother who taught you the most important skill of listening known as In One Ear And Out The Other.

The truth is that there is no such thing as a literal week of abstinence for healthy young couples seeking 99% effectiveness at avoiding pregnancy. The real fertile window is about six days plus typically an additional three days to verify the end of fertility, resulting in nine days of abstinence as the absolute minimum. Real world averages look more like a week and a half to two weeks.

Unless you are using high-tech methods of fertility determination, you can expect a minimum of ten days of abstinence required to avoid pregnancy each cycle.

Some day you will likely find that this is no longer the case and you will note that your observations have changed to an actual week of fertility in any given cycle. When this happens you should have another serious conversation with your spouse about your family planning goals. It is likely that either you are using NFP in a less effective manner (which is absolutely fine if it is what you want!) or that your fertility is declining (which happens to us all eventually).

Averages are, of course, just that. You may live for years with slightly reduced fertility which requires less than a week of abstinence to avoid pregnancy. You may also live for years with hormonal quirks that routinely require you to abstain for closer to 75% of any given cycle when you need to avoid pregnancy. But if you are healthy, you can expect 10-14 days per cycle to be routine.

.  .  .

Please Note: this post is just what I tell my sisters. There are certainly people with better training  who would disagree. Check here for the best counter-argument I have seen. Unfortunately I have to chalk it up as compelling without being convincing, but you may live in a different world.

The Body , , ,


  1. I don’t think it serves anyone to sugar coat the demands of NFP. I’ve seen a lot of presenters do that. I think if you’re trying to be careful, it’s much more like two weeks. That can be difficult when you’re dealing with busy schedules during the non-fertile times. Just saying…let’s keep it real.

    Does this make me a superstar commenter now? ;-)

  2. One thing that very few NFP teachers/cheerleaders address is that there is a tradeoff between more effective/less abstinence. It’s common sense when you think about it, but rarely addressed.

    A good NFP teacher should teach the couple not only to detect possible fertility, but to have an understanding of just how likely sex will lead to pregnancy on any given day. Is the couple using a possible, but low risk day or are they practically trying to conceive?

    I think some NFP instructors take the attitude “if you aren’t using NFP the most conservative way, then you are TTC.” or worse, “if you aren’t using NFP the most conservative way, then you don’t really have serious reasons and shouldn’t be using NFP in the first place.”

    (We’ve run into this. It was NOT helpful.)

    But that’s not the instructor’s role. NFP is objectively morally licit. Deciding how conservatively to use it is part of the conversation the couple has to have in discerning their marriage vocation. Just how serious are your reasons for avoiding pregnancy:

    Do you have a very serious reason to avoid pregnancy? If so, then you will need to use NFP very conservatively.

    Do you have a good reason to avoid pregnancy, but it wouldn’t be the end of the world if you got pregnant? Then you may want to use the “possibly fertile, but probably not” days.

    And that is going to be different for each couple in each situation.

    • Rae

      I agree. Thankfully I think that only CrMS has this failure of comprehension as an actual part of the method. And most people still have common sense enough to realize that there is a difference between a day with a 2% chance of pregnancy and a day with a 25% chance.

      Thank goodness that regardless of what a few people may happen to think, we now live in a time with many approaches to NFP that couples can customize for themselves!

      • Yes, CrMS does, unfortunately, make this part of the method. While common sense says that some days are more fertile than others, taking an all-or-nothing approach to instruction may leave the couple guessing and taking greater risks than they realize.

        Fortunately, thanks to the internet, there is a LOT more information about NFP now that is freely available than there was only 10 years ago. That’s a huge difference.

  3. As for this post vs. the “counter-argument”: This post (and the cited studies) talk about the average, while the counter-argument is talking about the ideal.

    The point of the counter-argument is that NFP instructors should be helping couples address health issues so they can have the shorter “ideal” periods of abstinence.

    Perhaps she is overly optimistic at just how much an instructor can solve, but I’ve seen way too much of “well, that’s just how you are, just suck…er…offer it up” from instructors when sometimes there IS something that can be done.

    A big reason why couples get frustrated with NFP (and why we got frustrated with it in the past) is because they aren’t getting help with method issues. NFP is science and should be taken seriously as science.

    [Full disclosure: After reading the counter argument, we signed up for classes with the instructor who wrote the article, Kristin Putnam. Turns out that she found that Mrs. W. (age 30) had a minor issue that was easily fixed. When it was, our abstinence was reduced from 10-14 days to 7-9 days. We were very satisfied, but, as always, YMMV.]

    • Rae

      That is awesome that she was able to help you! I still can’t understand the science behind how less than 9-10 days could be the scientific “ideal” for a healthy couple in their early 20s, but no one is 22 forever and help with method issues is a fabulous gift.

  4. I had a very snarky comment about “fertile” days and “wasted abstinence” but I will refrain ;).

    Instead I will say that I love this post and we try very hard to represent the method accurately AND take our responsibility as teachers very seriously in our willingness to follow-up with and continue to help out couples after the formal classes are over. I really think anyone who wants to teach NFP (of any kind) should be committed to that…we called our teachers for months with questions.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>