If you test for LH, this article is very informative

Found this great article about testing for LH surge: The use of urine LH detection kits to time intrauterine insemination with donor sperm

Just thought I would share. I use the CBFM which tests in the AM and just added the CB digi opk to see if I could catch it sooner and clearer (no line reading). And just like this study suggested, I tested this AM and it was negative and tested again at lunch (3pm) and it was positive! Apparently while surges generally happen in the AM, you are testing hours old urine that does not have the lh concentration yet. This might help estimating ov if you are timing your attempts closer to it. Also it suggests that insemination is more likely 18-53hrs after the initial positive for achieving pregnancy.

Wow, that is interesting! I have heard that it is best to test for the LH surge starting mid-day. Its also interesting that they had the best results 18-53hrs after the surge! Definitely good info! Thanks for sharing!

bump