I've never done nor do I endorse this, but something occurred to me while we were tracking my cycles to TTC our second born...
In my experience, Ovulation Predictor Kits almost always show a second line anytime of the month (especially with first morning urine) and most just have the brand name on them. What makes an OPK positive is whether or not the test line is darker than the control line, not just the presence of a second line. On a HPT, any second line indicates a positive.
the naked male eye, there is no difference between a Home Pregnancy
Test and Ovulation Predictor Kit. That means any broad could walk into a
dollar store and buy both the HPT and OPK, then swap them out. Voila!
"See that second line? I'M PREGNANT!"
Kind of scary, huh? Get the word out. If you have a guy friend/son/family member making life decisions based on a positive pregnancy test, insist that he confirms the pregnancy with a doctor.
Just a very dangerous thought. For the record, I already have my desired DH and children.