Ovulation Predictor Kits

Ovulation predictor kits are home test kits that are used to predict ovulation. They work by detecting the LH (lutenizing hormone) surge in your urine that typically indicates that ovulation is fast approaching.

Although ovulation predictor kits (OPKs) can be expensive, they are considered to be a reasonably effective method of predicting ovulation because they are able to detect the LH surge that typically appears 24 to 36 hours before ovulation. They're not, however, considered to be as reliable as high- and low-tech ovulation prediction methods that either detect estrogen in the urine or monitor changes to the cervical mucus—the current "gold standard" of ovulation prediction.

What they can't do, however, is tell you when to start having sex. Ideally, you should be doing that before the LH surge appears. (The best time to start trying to conceive is three to five days prior to ovulation.)

One other word of caution: The fact that you have an LH surge does not necessarily mean you're ovulating. LH can surge with or without the release of an egg. To make matters worse, it's possible to have a series of LH surges prior to the "real" one—something that can throw your timing way out of whack.