The above link is to a website with OPK (Ovulation Predictor
Toni Weschler covers the OPK issue thoroughly in her wonderful
book, "Taking Charge of Your Fertility", commonly referred to as "TCOYF" around the TTC/fertility message boards and chats.
Toni Weschler also helped design the fertility charting software called Ovusoft, and there is a page on the Ovusoft site with info about Fertility Myths that are so often perpetrated in our society. (The underlined
words are links you can click on.)
I'd say if you choose to use OPK's, use them in combination
with charting your cycle, as one more tool to incorporate into your overall cycle interpretation. The thing is, you can get
a positive OPK and then your body can delay ovulation for any reason much longer than the one or two days the package
directions indicate, leaving you in a lurch if you only baby danced (BD/had sex;) when the OPK indicated you should.
Also, you can get a negative OPK and still ovulate soon afterwards (this has happened to me, as well as countless
Toni Weschler also mentions that some women have to
use OPK's twice a day, in order to raise their chances of 'catching' their OPK's surge at the right time, which can sometimes
register for only a couple of hours on the OPK's. Also, you have to be careful not to drink too much liquid before testing
and avoid going to the bathroom for two to four hours before testing, in order to increase the accuracy of the test
Pros and Cons of Ovulation Predictor Kits (OPKs)
Best Pregnancy and Ovulation Test Brands