Yes, they work, for most people. As Graciesmom528 said, they detect the LH surge that occurs prior to ovulation. You pee on the stick, preferably at the same time every day, and you want the test line to be as dark as or darker than
the control line in order to be read as positive. There may be a second line for many days and you may see it get progressively darker, but it's not positive until it's at least as dark as the control line. (The reading issue can be resolved by getting digital tests.) It works the same way whether you have a regular period or not, but without knowing when/if you ovulate, you could end up spending a ton of money before you actually get your positive. Best (and cheapest) thing to do is chart. Read Taking Charge of Your Fertility
by Toni Weschler and check out FertilityFriend.com
for good pointers. Good luck!
at 1:41 PM on Apr. 18, 2011