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    Ovulation Kit: How to Choose the Right Fertility Predictor for Maximum Accuracy

    Ovulation Kit: How to Choose the Right Fertility Predictor for Maximum Accuracy
    Updated 17 February 2022 |
    Published 19 October 2018
    Fact Checked
    Dr. Iryna Ilyich
    Reviewed by Dr. Iryna Ilyich, Obstetrician and gynecologist, medical advisor, Flo Health Inc., Lithuania
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    If you’re interested in monitoring your fertility, an ovulation testing kit can offer helpful insight. Predicting ovulation is helpful if you are trying to become pregnant. Ovulation predictor test kits project the release of an egg within hours or days. Each egg can be fertilized for up to 24 hours after it’s released. Let’s explore how to use ovulation kits to monitor your fertility if you're planning for a baby.

    An ovulation kit detects the luteinizing hormone (LH) surge that happens before an egg is released. Pinpointing this surge can tell you when to have sex to increase your chances of getting pregnant. The tests indicate when your body is entering the peak of your monthly cycle. Advances in medical technology have made ovulation predictor test kits one of the most reliable options for identifying LH surges. 

    What is an ovulation kit?

    Ovulation kits — also known as ovulation predictor kits (OPKs) — use a small urine sample to detect an LH surge. This tells you when you may be approaching ovulation. 

    The kit has two lines — the control line and a test line. The control line verifies that the kit is working. The test line reveals that your LH is surging when it turns the same color or darker than the control line.

    Types of ovulation kits

    Ovulation predictor kits are widely available at pharmacies and online retailers. Some of the most commonly recommended ovulation kits include the following:

    1. Fertility monitors

    Fertility monitors are electronic devices that track LH and estrogen levels in urine. Their main purpose is to predict peak fertility in each cycle. The device records your ovulation cycle and helps identify your most fertile days, which can increase your chance of conceiving.

    Before you begin

    To determine when to start using the chart, first calculate the length of your average cycle. Your cycle length is the number of days between the first day of one period and the first day of the next.

    NOTE: If you have irregular cycles, use your shortest cycle length to decide when to start the test. 

    Most fertility tests include these steps:

    • Try testing at approximately the same time each day.
    • Urinate into a sterile container.
    • Take the test card out of the case.
    • Hold the test strip in a vertical position with the arrows pointing downward.
    • Dip the strip into the urine approximately 1/4 inch and hold it there for at least five seconds. (Dipping the strip for longer will not produce false results, but be careful not to dip past the “stop” line.)
    • Take out the strip and lay it flat.
    • Read the results after 5–10 minutes (follow the instructions on the package).
    • If the control line is not visible, the test is invalid.
    • If the test line looks similar to or darker than the control line, your LH has surged.
    • If two lines are visible but the test line is not as dark as the control line, your LH level has not surged yet. 
    • Once your LH has surged, there is no need to continue testing.

    2. Saliva tests

    Saliva testing — also known as fertility ferning — is an easy method for figuring out your fertility window. Right before ovulation, a person’s saliva changes. If you look at a sample of this dried saliva under a microscope, it can reveal a pattern that resembles fern leaves. This pattern results from an increase in the level of salt and estrogen during ovulation.

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    How an ovulation kit works

    How do ovulation kits work? This is one of the most common questions people have when planning for a baby or wondering about fertility. Here is the answer. 

    An ovulation kit tests your urine to detect a surge in LH. While LH is usually present in your urine, it increases for 24 to 48 hours before ovulation. These tests help you identify those days that act as an invaluable tool in your baby-making arsenal. 

    One or two days before ovulation, your LH may surge by up to five times the usual amount. This time is your most fertile window. Having sex on these days increases your chance of conception.

    Tracking ovulation

    How to use an ovulation kit

    Since different kinds are available from various manufacturers, make sure to follow all the instructions on the package of the ovulation kit you use. Most of them share the same general instructions.

    1. Urine-based ovulation predictor kit

    For this test, collect your urine in a sterile container or place the stick under you as you pee. A colored band will appear on the test stick. The test card may display a positive sign, indicating an LH surge is occurring. This means ovulation will likely happen in the next 24 to 48 hours. A digital ovulation indicator kit uses a smiley face to tell you your most fertile days.

    Some urine tests can also check for high levels of estrone-3-glucuronide (E3G), another essential hormone in ovulation.

    To use your ovulation detection kit, follow these steps:

    • Try to collect your urine sample at about the same time each day.
    • Try to reduce your fluid intake for about two hours before using the ovulation tracker kit. Excessive fluids will dilute your urine, which will make detecting your LH surge more difficult.
    • Read the results on the test card within the time noted in the instructions. A positive result will not fade, but some negative results may display a faint second-color band if you wait too long.
    • Throw away the test stick once you have read the result. It’s not meant for reuse.

    2. Saliva test kit for fertility

    Saliva tests for predicting ovulation are also easy to use. First, add a drop of saliva to the slide and let the sample dry. View the slide under the microscope. If ovulation is about to begin, a distinct fern-like pattern will appear under the microscope. This fern-like pattern begins to appear around three to five days before ovulation. 

    Ovulation microscopes are reusable, discreet, and easy-to-use. They allow you to predict your peak fertility by assessing estrogen and salt levels in your saliva.

    To maximize the accuracy of your saliva ovulation test:

    • Do not eat, drink, smoke, or brush your teeth before the test.
    • Clean the slide or lens before using it.
    • If you wear glasses, remove them before viewing the slide under the microscope.
    • Pull the test slide out of the case.
    • Place a drop of saliva from beneath your tongue on the slide surface. Avoid creating air bubbles with saliva on the slide.
    • Allow the sample to dry for approximately five minutes.
    • Look into the lens. Adjust the eyepiece and push the LED light button to see the test result.
    • Clean the lens after every use.
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    How much do ovulation kits cost?

    Standard urine-based OPKs are the least expensive option. Most brands offer the same level of reliability, so you’re free to choose the one that allows you to do more tests at a lower price. 

    Digital ovulation test kits are available as paper sticks that change color or digital monitors with strips. Pricing varies depending on the kind you choose, and you’ll usually save money by opting for a simpler device.

    How accurate are ovulation kits?

    Are ovulation kits accurate? In fact, they appear to be more accurate than calendar-based and temperature methods at predicting your most fertile days.

    If used as directed, OPKs can predict your LH that precedes ovulation with 99-percent accuracy. But these tests can’t confirm whether ovulation actually occurs a day or two later. Some people experience an LH surge without releasing an egg, which would create a false-positive ovulation test result. There are a few possible explanations for an elevated LH level that doesn’t lead to ovulation. Here are some of them:

    • Luteinized unruptured follicle syndrome (LUFS)
    • Polycystic ovary syndrome (PCOS)
    • Genetic disorders (e.g., Turner syndrome)
    • Pituitary disorders
    • Perimenopause/menopause

    Problem-solving for a negative ovulation test

    Ovulation tests may seem frustrating while you’re waiting for a positive result that indicates your LH surge. In some cases, you can resolve the problem on your own. For certain issues, you may need to consult a health care provider. Let’s look at some of the factors that may cause a negative ovulation test:

    You may be testing too early or too late

    An LH surge happens 24–48 hours before ovulation. Some people only start testing right before the day that they expect ovulation to happen. However, the LH surge can be tricky to predict. Sometimes, it happens sooner than you may have expected. Alternatively, the LH surge may have only lasted for 10 hours. People who test for ovulation only once a day may actually miss the LH surge altogether. As a result, some health care providers suggest doing the test twice a day — a few days before ovulation and at least 10 hours apart — to pick up the LH surge.

    There are several explanations for multiple negative ovulation tests:

    • The peak time of LH may be too short to be detected. Sometimes, testing twice a day can resolve this issue.
    • Your fertile window and ovulation may have shifted earlier or later. Start testing for ovulation 17 days before you expect your period or three days before you expect ovulation.
    • The test instructions aren’t being followed. For example, if the urine was diluted or the device instructions were followed out of order, you may get a series of false negatives.

    You’re unsure of your menstrual pattern

    The LH surge happens at different times for different people. By keeping track of your menstrual cycles for at least six months, a pattern should emerge. This will help you determine when ovulation may occur.

    You may have an underlying health concern

    Possible causes of ovulation problems include:

    • PCOS 
    • Hyperinsulinemia and insulin resistance
    • Weight disturbances 
    • Adrenal disorders 
    • Premature ovarian failure
    • Ovarian cysts, tumors, or other masses
    • Hypothalamic and pituitary causes
    • Eating disorders 
    • Intense exercise habits
    • Stress
    • Medications
    • Thyroid disease
    • Renal and liver diseases

    If you’re concerned by your ovulation pattern, consult your health care provider, especially if you feel OPKs are not helping.


    Ovulation test kits are a great tool for people who want to determine their fertile pattern. A variety of options can help you monitor your cycle by pinpointing when ovulation is about to occur. Since most test kits offer 98- to 99-percent accuracy, choosing which ovulation test kit to use is up to you.

    If you’ve tried ovulation test kits but haven’t identified your ovulation window, contact your health care provider with any questions.


    Leiva, R., et al. “Use of Ovulation Predictor Kits as Adjuncts When Using Fertility Awareness Methods (FAMs): A Pilot Study.” The Journal of the American Board of Family Medicine, vol. 27, no. 3, 2014, pp. 427–429., doi:10.3122/jabfm.2014.03.130255.

    Su, Hsiu-Wei, et al. “Detection of Ovulation, a Review of Currently Available Methods.” Bioengineering & Translational Medicine, vol. 2, no. 3, 2017, pp. 238–246., doi:10.1002/btm2.10058.

    Tiplady, S., et al. “Home Ovulation Tests and Stress in Women Trying to Conceive: a Randomized Controlled Trial.” Human Reproduction, vol. 28, no. 1, 2012, pp. 138–151., doi:10.1093/humrep/des372.

    Wilcox, A. J. “The Timing of the ‘Fertile Window’ in the Menstrual Cycle: Day Specific Estimates from a Prospective Study.” Bmj, vol. 321, no. 7271, 2000, pp. 1259–1262., doi:10.1136/bmj.321.7271.1259.

    Qublan, H., et al. “Luteinized Unruptured Follicle Syndrome: Incidence and Recurrence Rate in Infertile Women with Unexplained Infertility Undergoing Intrauterine Insemination.” OUP Academic, Oxford University Press, 13 Apr. 2006,

    "Menstruation And Menstrual Disorders: Anovulation | GLOWM". Glowm.Com, 2020,

    "Anovulation Clinical Presentation: History, Physical, Causes". Emedicine.Medscape.Com, 2020,

    History of updates
    Current version (17 February 2022)
    Reviewed by Dr. Iryna Ilyich, Obstetrician and gynecologist, medical advisor, Flo Health Inc., Lithuania
    19 October 2018
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