I have been using clear blue opk since my first pregnancy. Clear blue shows a happy face referring to two peak days (first peak day morning and night, second peak day morning and night)..the third day it shows a blank face from morning itself, but if you have intercourse on the first peak day morning or night and second peak day morning until max afternoon, you have chances of getting pregnant, but later than 2nd day afternoon the chances aare almost nil though it shows a happy face on the second peak night. The reason it shows happy face on the 2nd peak night is though the egg is dropped, the surge will not go away that faster. This is my observation for years.View Thread