Originally Posted by
atomic sagebrush
You can't tell if you've ovulated based on your OPK getting lighter - that's not how it works. You can have your OPK go negative and not have ovulated yet, or you can have it stay positive for a day or more after ovulation. I had actually just written a pretty thorough explanation in another thread, I'll copy it below:
An analogy I like to use to help people explain what surging/OPK really is....
The LH surge is NOT ovulation, it doesn't make you ovulate, it's just like this signal your body sends to itself to say "ok everything is in place, let's ovulate at some point pretty soon here". It's as if your boss came to your office and stuck a post-it on your door that said "Call Cleveland by Friday". The Post It doesn't make you call Cleveland, and it isn't instantaneous. It's just a signal. (the post it note signifies the positive OPK)
You could see that note, come in, and call Cleveland right away. (this would be akin to having a surge and Oing all right in a row very quickly)
Or you could ignore the note for a couple days, leave it on your door, but still call Cleveland right away (this would be akin to having a positive OPK for a couple days even tho you already ovulated)
Or, you could take down the note right away but not call Cleveland and just remember to do it later (your OPK goes negative, but you haven't ovulated yet)
Or, you could leave the note up for many days and then not call Cleveland until the very last minute (having many days of positive OPK that culminates in ovulation)
Or you could take down the note, throw it in the trash, and never call Cleveland (so your ovulation is delayed or stopped)
You could even have your boss mean to put up the post it note but forget, or maybe you don't see it or it falls off or whatever (you never get a positive OPK because the strips are defective or your urine is diluted or you miss a day of testing)
The point is, the act of ovulation and the surge are connected but aren't cause and effect. The OPK surge doesn't make you ovulate, it signals to this other body part (your ovary aka the worker in question) that ovulation is desired and so the worker/ovary needs to do its job and call Cleveland/pop out that egg but it does that on its own timeline to a very great extent. All the pos OPK is, is a post it note from on high that tells you do perform a task but leaves the when, up to you or your ovary to decide. So you can have a pos opk that goes negative but still have not ovulated, you can have a pos OPK that goes on for many days and have already ovulated, you can have days and days of positive OPK and have Oed at the very start of them or not till the very end of them or smack dab in the middle, you can have even false positives (you get pos OPK but never O) or false negatives (you O without ever getting a pos OPK)