When to measure and when not to measure

One question about tracking the basal body temperature for natural family planning is when to refrain from measuring. If you are clearly sick and have a fever, NaturalCycles will detect your temperatures as abnormal and automatically exclude them. However, if you are just feeling slightly under the weather, or have been partying the day before, or simply sleeping significantly more or less than usual, your temperature measurement for that morning could be slightly shifted. This is not at all “dangerous” and it will not make you get green days during your fertile window. It could however cause you to get less green days as NaturalCycles provides the same level of safety for all types of temperature fluctuations.

It is therefore better to refrain from measuring for days where you don’t follow your normal rhythm. Especially if you haven’t just started measuring your temperature. NaturalCycles uses all of your data data from the first cycle you enter, when it analyses your new incoming temperatures and therefore, after three cycles or so, statistics become less crucial. Myself, I have now used NaturalCycles for 500 days and I have meanwhile acquired quite some statistics. I therefore only measure on days where everything is according to my normal every day schedule. For example, before this morning (Monday), I did not measure since Wednesday (see chart). Thursday was the Swiss national holiday so there was some drinking involved for both Wednesday and Thursday evening. Then, during the weekend, I slept considerably longer than usually. Since my data are not limited by statistics anymore, and I am not yet close to ovulation, it is fine for me to skip those 4 days in a row. I you have a look at my chart below you see that there is a nice line until today, probably since I skipped the days before where I’d otherwise get elevated temperatures due to sleeping in/alcohol.

Measures - NaturalCycles

I will summarize some useful rules of thumb that you could adopt for optimal temperature tracking:

  • For the first 3 cycles, try to measure as often as possible
  • For the 5 days before and after expected ovulation, try to measure almost every day
  • Outside these two scopes try to at least measure 4 mornings/week, but strictly don’t measure if:
    1. You get more than 2 hours of more/less sleep than usual
    2. You wake up more than 3 hours earlier/later than usual
    3. You drank more than usual the evening before and you feel the alcohol the following morning
    4. Skip the first morning after having traveled long distance to a different time zone
    5. You feel ill or have a fever

If you apply these guidelines, you should get nice temperature curves. There will of course always be some fluctuations, which cannot be avoided, but that’s normal and nothing to be concerned about. You should also try to avoid first measuring and then deciding whether to use the temperature value or not. That might bias your chart to look like you want it to, rather than what is actually correct.

When you have to measure the LH hormones with ovulation tests (OPKs), you don’t have to worry about more/less sleep or alcohol.

You should however try to not drink any liquids and not go to the bathroom at least 2 hours before measuring, preferentially more than 4 hours. Best is also to avoid taking the test in the morning. This might sound confusing, as pregnancy tests are best taken when you wake up, but the LH surge often starts in the morning, so if you take your ovulation test then you are more likely to miss your LH peak. Of course, if you don’t find a good time during the day to avoid liquids for a longer time, then the morning is to be preferred.

Happy measuring!