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My knowledge on this all comes from reading Toni Wechsler’s “Take Charge of Your Fertility” book and I recommend you have a read. It’s the basis of the algorithm Fertility Friend uses to predict ovulation. The main focus of TCOYF is charting basal body temperature. Monitoring cervical mucus (CM) and cervix position are secondary and using ovulation using OPKs are considered not much help at all. I’ll go through what I learned about each in turn and maybe some of the other ladies can share their own experience.


Temperature rises by about 0.25 to 0.5 oC after you have ovulated. This is due to the release of progesterone by the corpus luteum (the follicle that released the egg) which basically sending this signal for 12-16 days after the egg is released – this is known as the luteal phase – this is long enough for the fertilised egg to implant which in turn release HCG (the hormone detected by pregnancy tests) – its job is to tell the corpus luteum to continue to make progesterone until the placenta takes over.

So anyway – the day after ovulation, temperature increases and TCOYF will tell you that 18 high temperatures = pregnancy (not that any of us ever wait that long). FF will require 3 temps higher than your coverline (I’ll explain that in a minute) to decide you’ve ovulated.

The coverline is set at the highest temp of your previous 5-6 days (it uses a rolling window to figure out if your higher temp is high enough).

Things that affect temperature include drinking alcohol the night before, getting up late/early, disturbed sleep, illness. If you include this data in FF it will take account of it (generally by marking an unfilled circle on your chart rather than a solid one).

So how to temp (I’ll describe my personal experience later so as not to confuse things) – generally it is supposed to be the first thing you do when you wake up – turn off the alarm, put the thermometer in and wait. If you wake early and won’t get 2-3 hours sleep before your normal wake up time do it then and mark the time change on your chart. If you wake up late just mark that on your chart too. Don’t take multiple temps, it will only confuse the issue.

As for thermometer – TCOYF recommends a basal thermometer, digital one with only one decimal place (if yours has two, round it up or down accordingly). Some people prefer an analogue (glass) thermometer since they don’t beep but you should always shake it down the night before.

Things temping can also indicate are an inplantation dip (usually around 5-10DPO) and a triphasic chart which looks like you’ve ov’d again because you get 3 or more days of an even higher temp – these can both be indicators of pregnancy or not mean anything at all.

Personally I started temping mid way through my first cycle off the pill (I got to CD30-odd and no sign of AF so I gave it a go). It turned out I had already ov’d but I didn’t know that until much later. My first experience of it temp fluctuation was one day it plummeted and later that day AF arrived.

I have found that my BBT doesn’t vary much no matter when I wake, I used to go sit on the loo and take my temp, completely flouting the no movement rule – it worked fine. I also used a bog standard fever thermometer from the pharmacy – it was fine too. Alcohol affected me, but only if I had at least two glasses of wine the night before. Otherwise, my temps were always in my pre-ov range of below 36.4 before ov and above 36.6 after ov. You’ll learn what works for you.

One more thing, if you sleep with your mouth open you may find you need to temp vaginally (it’s exactly as it sou


  • BabyZebedeeBabyZebedee Posts: 2,421

    Cervical mucus

    This is something you are probably used to already – at different times of your cycle you may notice it when you wipe or in your knickers, you may just generally feel slippery inside (this may coincide with an increase in libido). At the very basic level just making a note of how you feel inside is charting CM.

    If you prefer to be more rigorous you can check by wiping before the loo (stick to the same time of day no matter how you do it) or check internally using one or two fingers. CM goes through a few stages which are hormone dependent. Least fertile is when you are dry – almost no CM. Mostly it will be creamy – like a fluid face cream and white or pale cream colour or a little thicker than this which is known as sticky CM. However, as the oestrogen starts to increase as ovulation approaches it will become more and more watery and then for one to five (typically) days before ov it will take on the consistency of egg white – you may notice it hanging from you when you go to the loo (yes it is gross).

    After ov, it will probably go back to dry before becoming creamy again in the 2WW as progesterone increases.

    My personal experience is I chose to test internally with two fingers (after my morning shower I would squat down insert two fingers and sweep them either side of the cervix and gently remove) I won’t lie, it took me at least three cycles till I knew what was what.

    Cervix position

    As I was testing CM internally it was easy to check where my cervix was. This is still as bit of a black art to me since I have small hands and couldn’t reach when I was fertile.

    So again, squat and insert one finger. Think about how the cervix feels (if it feels like the end of your nose it’s firm, if it feels more like pressing your lip it is soft. The hole in the middle, is it open or close? How high up is it? Can you reach it easily or not? High = fertile.

  • BabyZebedeeBabyZebedee Posts: 2,421

    OPKs and fertility monitors

    These all detect the surge in LH that occurs 24-36 hours before ovulation (some of the more sophisticated ones will detect increased oestrogen too to give you a high fertility reading ahead of the peak fertility that occurs when LH is detected). It is extremely important to note that just because LH surges, it does not mean that you will ovulate – all kinds of things can affect ovulation – stress being a major factor.

    So LH surges (I believe) about 6am, it then takes hours to find its way into your urine – the cheapy tests say to test about lunchtime for this reason – the digis say to test with fmu which I guess is for consistency.

    The other thing I need to warn you about is that some people have a false LH surge (I always did) where you will get a positive test but no ov. This is why it is important that you are charting your temp as only the increase in temp can confirm you have ovulated (well, that or a blood test).

    Personally I tried digi CB OPKs in my second cycle – I was already temping by then - and had a positive but got really frustrated when my temp didn’t go up – this was when I stopped using opks. I later realised I have false gear ups most cycles and I knew to keep DTD and just keep monitoring CM and temp.

    So all in all temping may seem a faff but believe me, within 4 cycles I was at the stage when I just started temping when I noticed I had EW and carried on till my temp went up. I knew 36.4 or less meant I was pre-ov and 36.6 or more I was post ov. The month we got out BFP I was only vaguely checking CM on holiday as I didn’t think I’d ov until we got back. I did have two patches of EW so I figured later that the second of those must’ve been when I ov’d but I actually had no idea I’d ov’d until we got back and I noticed I was kicking the duvet off. Next morning I temped to check and confirmed I had ovd. It’s worth the effort and a whole lot better than going for blood tests to check you’re ovulating.

  • Weddin crazyWeddin crazy Posts: 1,743

    Thanks, will def keep checking back to this over next few months I'm sure! 

  • BabyZebedeeBabyZebedee Posts: 2,421

    I really hope others will come to share their experiences too. I know different things work for different people image

  • Weddin crazyWeddin crazy Posts: 1,743

    Only thing I can't check is cervix, tried before but my ocd just made me go nuts thinkin bwt germs etc. couldn't handle it. hopefully trackin other stuff will do 

  • EllabellaEllabella Posts: 1,292 New bride

    Thanks for this.

  • MrsMacca2013MrsMacca2013 Posts: 854

    Great post, usually takes months of reading and trying things out to know all this so handy to have it one place image

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