I know I O’ed recently, but which day?

Here I am again – having ovulated recently but not being too sure of the day itself. With the positive ovulation predictor kit test (opk) last weekend I know I ovulated in the last week, but its unclear which day.

This is the second cycle where I have had a range of possible O dates instead of confidence in one particular interpretation. While its not critical to know exactly which day, I enjoy trying to solve the puzzle and better understand my body’s workings. So, here goes:

When I added my temperature yesterday morning, Fertility Friend finally suggested that ovulation had been confirmed by a third high temperature. But to my surprise it put ovulation on the same day as the positive opk.


Depending on the detector analysis method used, Fertility Friend suggests O anywhere from cycle day (CD) 16 to CD19.

The Fertility Awareness Method (FAM) detector, which follows the rules of the classic Taking Charge of Your Fertility book, puts it on CD 19. That method is purely based on temperature, but I’ve found scientific papers investigating the time between ovulation and temperature rise and it can be more than one day. So using temperature alone is really just an estimate. For the 2 cycles in which I used OPK’s, I had a longer than normal time between positive result and clear thermal shift. So a solely temperature-based detection method doesn’t seem adequate.

My LH surge appears to be short; I got a negative saturday night at 9:30, a positive sunday at 4, and a clearly negative by 8 pm sunday. So my LH surge was somewhere in the 22 or so hours from Saturday night to Sunday night. It usually starts while you are asleep so we could assume the surge started the night before CD 17 and peaked in late morning or so on that day. Ovulation is usually 12-36 hours after the LH surge, which would put it at anywhere from late CD 17 to CD 18.

I thought I felt ovulation on CD 18, but maybe it’s possible that the cyst-like pain could have been corpus luteum alone rather than the dominant follicle before the egg was released.

So the OPK based method suggests CD 18, the day after the positive OPK. That is also the strongest O pain with the feeling like a cyst in my left side, so I tend to lean towards that day.

So I don’t think that the FAM-based suggestion of CD 19 is right because my pains and OPK results suggest CD 18 at latest.

The advanced detector method which incorporates temps, CM, CP, and OPK, puts it on CD 17 (day of opk +), presumably because I had a slight temp rise the morning of CD18 and then not another until CD20.

Finally, the FF research detector puts it on on CD 16 (before opk +!), at the lowest temperature point before a stepwise rise.

All in all I’m leaning towards CD 18 with some possibility of CD 17, and am thinking its not likely to be CD 19 or CD 16.

If any readers are knowledgeable about charting, I’d love to hear your thoughts!

PS click on this ticker to see my current and past charts:


10 thoughts on “I know I O’ed recently, but which day?

  1. I would guess CD19. It is also the last day of fertile mucus. Depending on what time of day you did the OPK, I would either say that it was accurate or not.
    Can you link me to your chart homepage? I may be able to give you a better answer if I can see it more clearly, as well as your chart history.
    (P.S. – I did FF’s charting course, if it helps. And I am an obsessive chart analyzer.)

    • Hi Little Duckies!

      Thanks for your comment! I also have pictures of the OPK’s in my previous post. I took two on the day of the positive and the 2nd was already negative. The next day I took it at lunch time and it was negative too. Last cycle I also had a mismatch between opk results and a temperature-based analysis

      It definitely occurred to me that the pattern looks like those fertile days were right after BD, but whenever we BD I don’t check CM until the evening instead of the morning, and I’m not sure what else I could do. Seems like that should be enough time. The first time I checked in the morning after a bd I could tell it was semen and this wasn’t like that so I think it was truly the CM. I hope anyhow!

      I’ll get the link for you 🙂

      I haven’t completed the course but I read (and reread) their Charting your way to Conception book which I think is the same content.

      • It could be that your LH peak is 36-48 hours before ovulation, instead of the standard 12-24.

        I didn’t even check the BD pattern against the CM pattern. What threw me off was watery CM on CD23 – which I was wondering if it was arousal fluid/BD leftovers. The first two months that I charted, I mixed the two up, until I saw EWCM and then suddenly it all clicked. How do you check CM? I usually just look at the toilet paper – right after you go, you get all the BD leftovers out the first couple times, and then the next time you go, you can usually see real CM.

        Yeah, I didn’t do the course itself, because I didn’t have patience, just took the test and ended up with a 92 or 95 or something like that. All from reading the book and the FAQs.

      • Yeah the CD23 watery was an odd occurrence, but it was about 20 hours after BD which had been before bed the night before, so I don’t know what’s up with that. Usually I check internally but the CD23 there was so much I could feel it and it just leaked out so I saw it when using the bathroom. I had a similar experience the day before too, both in the evening.

        Yeah I may have O’ed more than 30 hours after surge, but I’ve also read (outside of FF) that temp rise can also be more than the usual day after O, so I’m wondering if there is anyway to tell which it was. Maybe the last day of fertile CM is a good clue like you said.

        If I may ask, how many months did it take you to conceive your children?

      • I would say if it was 20 hours later – that it was from BD. You can generally tell if you play with it a bit, because BD stuff breaks really easily and it’s more white than clear. But, no way to know. I started using the “notes” section to write stuff that I’m unsure about – that way it’s there and you can check it, but it’s not “on” your chart.

        I don’t know. BUT, if you have the same pattern a few months in a row, it’s probably safe to say that that’s your pattern and you will see a + OPK, two days later O, and then a temp rise. Or whatever. Everyone is different…

        DS came three months after our wedding; I wasn’t charting – just “not preventing, not trying” kind of thing. Then a few months after I stopped nursing, I realized it had been 10 months since I got my first PP period (we had been trying since his 1st b-day), I went to a doctor – he thought I was O’ing, but based on OPKs, I didn’t believe it. I set out to prove that I wasn’t O’ing and started charting…and caught the tail end of the no-O phase: no O/short LP, early O/short LP, normal cycle. The second normal cycle I got pregnant….and then miscarried two weeks ago, at 11weeks. 😦

      • The odd CD23 one didn’t stretch at all, it was very clear and shiny and low in viscosity – like water. When I’ve actually thought it was semen, it usually had more stretchiness and higher viscosity and was whiter, but not as stretchy at when I thought it was EWCM. It could have been my own arousal fluid,but we were out and about in the city and had been walking and eating dinner, I wasn’t feeling aroused anyhow.

        I think classifying the CM can be pretty hard! So I use the notes for that too, to describe it more so I can come back and be like, should I really have marked it as that?

        Haha yeah glad the 3 months after was conception not delivery, wouldn’t be too fun to be 6 months pregnant at your own wedding!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s