Positive opk when pregnant.

Kristin • Been married 8 yrs, actively TTC for 6 yrs. I have PCOS & insulin resistance and never ovulate. My cycles are 100+ days. We just finished our fourth round of clomid.
Do opk's always turn out positive when pregnant? Or can you be pregnant and have a totally blank opk? Just curious if that's a quick way to see if I'm out this month?