The Trying to Conceive and Just Starting Out Primer

This is a "primer" created by Krista (Rudylover) and posted by Jennifer (Tigger062077). We made this as a source of information for the "newbies" who are afraid to ask a "silly question"...and for the "oldies" who have been doing this so long they've forgotten the basics.

If you want to reach us, you can reach Jennifer at and Krista at

Wednesday, August 10, 2005

Ovulation Predictor Kits (OPK's)

Ovulation Predictor Kits (OPK) are urine tests that detect a surge of Luteinizing Hormone (LH) in your urine. LH is present in most women’s urine all of the time to some extent, but it surges just prior to ovulation.

OPK usually come with 5 – 10 tests that you dip into your urine or hold in your urine stream. You begin using a test each day a few days prior to when you believe you will ovulate until you get a positive result. Most women stop testing after they get a positive result. Most people agree that it is best to test somewhere in the hours from late morning through early evening. It is believed by many experts that LH often surges in the early morning hours and then takes several more hours to be detectable in your urine, which is why they advocate testing later in the day. Some women do prefer to test 2 times a day to be sure they do not miss the LH surge, but most women will be able to catch their surge by testing once a day.

You follow the instructions with the OPK and then evaluate the results. As with pregnancy tests, there is a control line and a test line on the stick. The major difference is that with most OPK, the test line must be as dark as, or darker, than the control line to be considered a positive test. Many women have a light test line every time they test, but this is not a positive OPK. The line must be dark like the control line.

OPK can be used on their own, or in conjunction with charting your other fertility signs. You will probably learn the most about your cycles if you use OPK in conjunction with charting at least some of your fertility signs.

OPK are great tools but they are not fool-proof. The results can be interpreted differently by different women and an important thing to note is that you can get a positive OPK and not actually ovulate soon afterwards. It is possible to have a surge of LH as your body prepares to ovulate, but then the egg is not actually released for whatever reason. When this happens, your body will likely try to ovulate again, and so you may have another surge of LH if that happens. If you are temping, you would probably see that your temp did not rise within a few days after a positive OPK. That might clue you in to start testing with OPK again to see if you get another positive, followed by a thermal shift, which gives you more reason to believe you really did ovulate around that time in your cycle.

There is a great FAQ section on OPK at Pee On A Stick.Com and I highly recommend you read it if you plan to use OPK.