Basal Temps and how they work

Ok, now bear with me cuz I haven’t had formal training on NFP or anything but a question arose when talking with a friend of mine about NFP.
You know how you’re supposed to take your temps every morning at the same time? What if you’re off a few hours, like sleep in late for a couple of days? Will that affect your fertility reading?

From what I have read, taking your temp at the same time every day insures that you get a constant pre-awake temperature.

The longer you wait after that time in the morning your temperature will naturally go up until it reaches your body’s normal waking temp. Does that make sense? Maybe someone else can explain this for me.

Anyway, this hasn’t always been the case for me. About half the time my temp stays in the normal 6:30am range and the other half of the time my temp is 98 or above. This is why with the STM you also cross check with CM.

My husband and I have been a SERENA accredited NFP teacher couple since 1982. I’m wording this as I would to a client.

Basal body temperature is the temperature of the body at rest, so the ideal is to take your temperature the first thing you do and at the same time every morning.

However, in real life, things happen. So you woke up an hour late, now what?

Take your temperature as usual, and note the time on your chart. That way you can take this into account when evaluating your chart.

However if this is not an isolated instance (ie you are working shifts) I would recomend contacting your NFP provider.


I have just started using NFP,but from my understanding your temps should be taken within a specified hour. If you forget or are late a lot I would not rely on your temps too much. Pay close attention to your mucus, and I would definetly do internal oberservations. I would suggest setting your waking temp time later if you keep over sleeping. I don’t take mine til 9:00.

What if you wake up at different times due to changing work schedules and you have irregular CM patterns? Then what? How will you know when you’re fertile or not? I’m asking this to see how accurate it would be in a serious time to postpone a pregnancy.
Sorry for all the questions but I can’t afford to take the class right now and I had some questions about it from talking with friends who have just started using NFP.

Does anyone know about the Creighton method (I think that’s it! :o ) I was told that its a little different and there are some advantages to it.

I don’t actually take my temp at all. I found it difficult and misleading, and when trying to avoid, I did not want misleading.
I go by mucus, and chart it, and it produces a definite pattern every month.
I used to be worried that NFP couldn’t work. It does.
A teacher will advise you to abstain for a while as you begin to chart as seminal fluid can obscure your mucus pattern.

I use Creighton…er I did but I’m not charting right now :slight_smile:

From what I understand, Creighton differs because it only goes by your cervical mucus, so you don’t take your temps or do internal exams. I like it because it is simple and can also be used to spot health problems and stuff (because your mucus patterns are sign posts for which hormones are rising or lowering in your body, and health problems like ovarian cysts mess with the hormones, so you notice if something is amiss).

As Apricot Yougurt mentioned, if you start learning it and you’re already married you’ll have to abstain at first so you can learn to make good mucus readings…I learned Creighton the 6 months before the wedding, so I pretty much ignored the seminal fluid thing…LOL, now I understand what my instructor was talking about.

You basal body temperature can rise in the morning as fast as 1/10 a degree every half an hour. So if you regularly take your temp at 7am but take it at 7:45 its probably going to be off about 1/10 of a degree. So you just take it when you do, and mark it as a distrubance. Make a note of what time you DID take it and leave it at that.

Usually that temp won’t be important in your overall fertility pattern, but if it results in skewing your pre-shift six you can shave it, and if it comes during the time during your thermal shift you can usually just put your thumb over it and discount, wait an extra day. So its no big deal.

But if it becomes a habit of constantly not taking your temps at the same time each day then the temperature part of NFP symtpo-thermal will be misleading and shouldn’t be trusted. You should go on mucas only then and I would suggest getting in touch with Creighton instructors.

Hope that helps! God Bless.

Have you looked at your local library for The Art of Natural Family Planning? It will explain all the questions you or your friend might have. You can purchase the book online from new for $13.57 or used from $8.81. It might be something to think about with the money is available. It really is an incredibly valuable resource.

Good luck!

Thank you all for helping. What if I miss taking my temps at the same time every morning and also have irregular CM patterns? Then what?

I know you said your waking time was different due to work hours. Is there not anyway you can choose a time (say 6 am or 4 am?) and use that for temps everyday, or is it 3rd shift work? Temps are most consistant when you take them at the same time everyday, but personally, I’ve noticed very little difference when I take my temp either 1 hour earlier or 1 hour later. However, if the need to avoid is great, I would investigate either Billings or Creighton, which are mucous only, even with irregular mucous patterns. You can learn to distinguish the pattern with a good teacher. Another idea might be to use a fertility detector (I know there are some out there, I have no idea what they are called, try searching this site for links) which are expensive, but in the long run, if needed, would be helpful.

You also might try contacting CCL for further help in this matter. They are the experts and would be able to offer more concrete advice for your situation.


can you be more specific on your irregular mucas patterns? Do you have any charts to reference? Do you have mucas all the time, or just one day have fertile mucas and the next day be dry?

There are so many explanations for irregular mucas patterns, so again I’ll reiterate what everyone else has said; to call a CCL teacher, or find some other teacher and take a class. If you can’t afford it right now then I would get “The Art of Natural Family Planning” and I would also get “Fertility and Nutrition” because a lot of irregular mucas patterns can be “fixed” with supplementing with vitamins or something else.

yes, try the book Fertility, Cycles and Nutrition by Marilyn Shannon it can help clarify the mucous pattern


The bottom line is, if you are really trying to postpone pregnancy for a serious reason, and trying to use NFP to help you do so, then you need to really be serious about taking your temps consistently. Especially if you have not so easy to interpret CM.
I am currently using NFP to postpone pregnancy and I have a 9 mo. old baby. However I was just wondering what are some opinions about what constitutes a SERIOUS reason.

The only reason we waited before trying for baby number two was so I could lose the weight from the first. I am overweight to begin with and didn’t want another 20lbs tacked onto the first 20lbs.

Yeah, I gained 55lbs.!!! But I lost it pretty quick. I can’t say my body looks the same, but my scale does. My baby girl was worth every lb. even if I didn’t lose an ounce though. I think that nursing really helps the weight come off. If God doesn’t choose to bless us with another baby by next summer I think we will probably stop charting.

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