Do opks work as pregnancy tests?

The short answer is yes. The long answer is a bit more complicated. Hcg and LH have similar structures with one end being identical and the other being different.

That being said, ovulation tests are looking for the alpha molecule while the pregnancy test looks for the beta molecule.

That means the pregnancy test won't pick up the LH but the ovulation test will pick up the hCG.

But it doesn't stop there. So the ovulation tests aren't as sensitive as the pregnancy tests. So if you're getting a blazing positive on the opk but stark white on the pregnancy test, some things wrong. Also, yes the opk has to be just as dark or darker than the control line.

My proof

Tests with the rings were at 11 dpo and the next set is 16 dpo. Also pointing out how horrible the cheapie are for detecting pregnancy. Only good for line progression. In my opinion