Devices and Tests for Measuring Fertility Status

Lesson 10

Fertility Monitor, OPKs, Saliva Microscope

Lesson Objectives:

  • Understand how devices and tests (saliva microscopes, ovulation prediction kits and fertility monitors) can be used in conjunction with fertility charting

  • Learn how to chart your test/device results if you choose to use tests and devices while charting

Major Points in this Lesson:

  • The use of devices and tests to monitor your fertility status is considered optional.

  • Commercial fertility devices detect the presence of hormones or their effects in your urine or saliva.

  • Saliva Microscopes respond to the presence of estrogen and show "ferning" when estrogen levels (and your fertility) are high.

  • Ovulation prediction kits respond to luteinizing hormone (LH) and are "positive" just before ovulation when you are most fertile.

  • Fertility Monitors and "advanced OPKs" respond to both estrogen and luteinizing hormone and indicate fertility is "high" when estrogen levels are high, and "peak" when they detect a surge of luteinizing hormone (LH).

  • Devices can be useful for cross-checking your primary fertility signs but are not essential for having an accurate and reliable chart.


There are an increasing number of commercial products on the market designed to indicate changes in fertility status. They rely on changes in your hormones that can be detected in your urine or saliva. When using these kits and devices, follow the manufacturer's instructions as closely as possible. Most manufacturers of fertility devices provide a toll-free number so that consumers can ask questions about the use of the devices. Specific questions about a particular device are usually best answered by the manufacturer of the device.

These kits and devices can give additional, secondary clues about your fertility status that can complement the observations you make from your primary fertility signs. You may find them especially helpful if it is taking a long time to conceive or if you find that you are not able to get clear readings from your cervical fluid and BBT signs.

Fertility tests and devices are not absolutely essential, especially if you are easily able to recognize the changes in your cervical fluid and other fertility signs, but you may find that you like to have the added information for cross-checking.

No device or kit that you can use at home can pinpoint ovulation as well as your temperature data. This is because only a thermal shift shows increased progesterone which is the hormone you release after ovulation. They can be quite useful, however, for timing intercourse and showing you when you have increased fertility in the days before ovulation. The decision whether or not to use such devices is personal and cost-related.

Saliva Microscopes

Saliva microscopes may be used to indicate your proximity to ovulation. They work by measuring the effect of estrogen in your saliva (or cervical fluid). When estrogen levels are high, when ovulation is approaching, saliva microscopes show a "ferning" pattern. Saliva or cervical fluid crystalizes into a ferning pattern that you can see on the slide of a microscope at this time. If you choose to use a saliva microscope, we recommend following the manufacturer's instructions as closely as possible to obtain optimum results.

Ovulation Prediction Kits (OPKs) and Fertility Monitors

Ovulation Prediction Kits (OPKs), also sometimes called Ovulation Prediction Tests (OPTs) have become quite popular and can be quite useful to help you find your fertile time. OPKs work by measuring the presence of Luteinizing Hormone (LH) in your urine. LH surges about 24 hours before ovulation. This causes your ovary to produce enzymes which in turn cause the dominant follicle to rupture and release the ovum into the fallopian tube. This is ovulation. An OPK is thus expected to be positive the day before you ovulate. It is also not unusual to see a positive OPK result the same day you ovulate. Following a few guidelines can help you get the most out of your OPK.

  • Like any product, follow the manufacturer's instructions carefully.

  • If you do not test every day from before you expect to be most fertile, you may miss the surge. Likewise, if you test too late, you may miss the surge.

  • Testing daily once you have started to test is the best strategy. Your first positive OPK result probably means that you are about to ovulate. Since OPK packages include only a limited number of test strips and are fairly expensive, timing when to start testing is crucial.

  • Follow the manufacturer's instructions about the time to take your OPK. First morning urine may not be the best for OPKs since your LH surge usually begins in early morning when you are still sleeping and may not be apparent in your first morning urine. If you test in the early morning, you may miss your surge entirely since LH levels may already be reduced by the next morning. Late morning or early afternoon is usually best unless the instructions (or your doctor) suggest otherwise.

  • Unless the manufacturer's instructions suggest otherwise, record your OPK results as positive if the test line is as dark as or darker than the control line. Record your results as negative if the test line is lighter than the control line. For digital tests, follow the manufacturer's directions.

  • Do not rely exclusively on OPK results to time intercourse as you may not see an LH surge (positive OPK) even though you may be fertile. Your increased fertility begins before you see a positive OPK result since sperm can live in the reproductive tract for a few days in fertile cervical fluid.

  • During your potentially fertile time, have intercourse at least every other day even before you see a positive OPK result. Switch to every single day once you see a positive result until ovulation has been confirmed by your temperature data. (Talk to your doctor about intercourse frequency if you suspect any sperm issues).

  • If you are taking Clomid, ask your doctor or the OPK manufacturer when to start testing with OPKs.

  • Fertility Monitors and some advanced digital OPKs work by measuring the presence of both estrogen and Luteinizing Hormone (LH) in your urine.

Recording Data from Kits and Devices on

If you use a saliva microscopes you can record:

  • No Ferning

  • Partial Ferning

  • Full Ferning

For Ovulation Prediction Kits, you can record:

  • Positive

  • Negative

For Fertility Monitors (and OPKs which measure both estrogen and LH) you may record:

  • Low

  • High

  • Peak

Select "Tests/Monitors" on the data entry form on your Fertility Friend App to enter your test results. You can customize your form to display the tests you use regularly.

Test data entry

The test data entry on the web site is similar.

Next Lesson: Additional Secondary Fertility Signs.

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