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Ovulation Test Kits: How They Work

Learn how ovulation test kits detect your fertile window by measuring LH surges, helping you time conception with accuracy.

Health Screening

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Published on 29 Apr 2025

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By Thomson Team

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What is an ovulation test?

An ovulation test, or an ovulation predictor kit, is designed to check your urine and help you identify the most fertile days in your menstrual cycle.

Ovulation tests detect a rise in hormones, specifically the luteinising hormone (LH) in your urine. This hormone rises sharply 24 to 36 hours before ovulation, and a rise in this hormone signals the ovary to release the egg. Thus, this test can help you predict when an egg release is likely, aka when you are most fertile.

Some advanced tests also measure oestrogen levels, which rise just before the LH surge, providing additional insight into your fertile window.

What is inside an ovulation test kit?

An ovulation test kit typically contains the following items:

  • Ovulation test strips or sticks:

    • These are the main testing tools used to detect the surge in luteinising hormone in your urine, which signals that ovulation is likely to occur soon.

    • The number of strips or sticks per kit can vary, with some kits providing a single test and others offering multiple (e.g., 5, 20, or even 50) for daily testing.

  • Instruction leaflet:

    • Every kit includes detailed instructions in English (and sometimes other languages) explaining how to use the test and interpret the results.

  • Urine collection cup or dropper:

    • Some kits provide a small disposable cup for collecting urine, while others include a dropper for transferring urine onto the test strip or cassette.

  • Rubber cap or protective cover:

    • In some kits, a rubber cap is included to cover the absorbent end of the test after use, helping to keep the process clean and hygienic.

  • Desiccant or silica gel packet:

    • This accessory is included in many kits to keep the test strips dry and free from moisture until use.

Depending on the brand and type, digital ovulation test kits may also include a digital reader, similar to a pregnancy test, that displays results in a clear format, such as a smiley face or text.

How can an ovulation test help me get pregnant?

Knowing your most fertile days during your menstrual cycle is vital since you can only get pregnant a few days each cycle. This information allows you to time intercourse during your most fertile days, which are the day of ovulation and the few days before ovulation.

Measuring basal body temperature will only tell you that you have ovulated after your ovary has released an egg, and since eggs only live for 12 to 24 hours, it may be too late to start trying that month.

Thus, there is a wide range of ovulation tests and fertility monitoring products available to help you detect the rise in the luteinising hormone (LH) or both LH and oestrogen. This will help you better understand and track your body's ovulation cycle. Therefore, you can identify your most fertile days to enhance your chances of conceiving naturally.

When should I take an ovulation test?

When to take an ovulation test depends on your menstrual cycle length and the test type. Typically, a woman's menstrual cycle is 24 to 38 days, with a standard reference timeframe of 28 days.

Usually with a 28-day cycle, you will ovulate on day 14. For a typical 28-day cycle, start testing around day 10 or 11. If your cycle is shorter, begin earlier, and for longer cycles, start later, as the ovulation day varies depending on your cycle length.

Generally, you should begin testing 3 to 5 days before your expected ovulation day and continue daily until you detect your LH surge. For best results, take the test at the same time each day, ideally in the morning, when LH is most likely to be detected in urine.

Which ovulation test is right for me?

There are several types of ovulation tests available:

  • Test strips:

    • Affordable and widely available, these require you to dip a strip into a urine sample.

  • Digital tests:

    • These provide clear digital results and are easier to read but tend to be pricier.

  • Fertility monitors:

    • These track LH and sometimes oestrogen for a more comprehensive view of your cycle, often storing data for several months.

If you have irregular cycles or conditions such as PCOS, consider a test designed for irregular cycles or consult your healthcare provider for more personalised recommendations.

If you are unsure what type of test is suitable for you, don’t hesitate to request an appointment with Thomson Medical. Our fertility specialists will help you to answer any questions you have and provide you with tailored recommendations.

How do I use an ovulation test kit?

It is best to read the instructions in your ovulation test kit, as not all tests work the same way. Before taking an ovulation test, do not drink large amounts of water to prevent it from diluting your urine. Take note of any medications you are taking that may affect your LH levels, such as birth control pills containing oestrogen or progesterone.

For the test itself, you will usually follow these steps:

  1. Unwrap a test stick and remove the cap from the absorbent tip.

  2. Insert the test stick into the test holder and listen for it to click in place. The test-ready symbol will appear on the test holder.

  3. Place the absorbent tip of the test stick in your urine stream for 5-7 seconds. You can also collect a sample of your urine in a clean, dry container and dip the absorbent tip of the test stick into the sample for 15 seconds.

  4. Leave the absorbent tip pointing down for about 20 to 40 seconds until the test-ready symbol begins flashing. Replace the cap on the test stick and wipe off any excess urine.

  5. Within 3 minutes, you should get a test-ready symbol. The display will show either an empty circle, indicating a negative result, or a smiley face, indicating a positive result. If the test ready symbol doesn't start flashing, then the test did not work, and an error symbol will appear on the display within 10 minutes. You will need to take the test again using a new test stick.

  6. Press the “Eject” button to remove the test stick. Wipe the test holder clean and wait until the display clears before inserting a new test stick.

  7. If the version you're using is not digital, the results will appear as a single (not fertile) or double line (fertile).

How do I read and interpret my ovulation test results?

  • Test strips:

    • Two lines will appear. If the test line is as dark or darker than the control line, it is positive, indicating an LH surge and likely ovulation within 12 to 36 hours.

  • Digital tests:

    • When they detect the LH surge, they usually display a clear symbol, such as a smiley face.

If you miss a day of testing or have an irregular cycle, you may not detect your surge, so consistency is key.

How much are ovulation test kits?

The price of ovulation test kits in Singapore varies depending on the brand, type (strip or digital), and the number of tests included in the kit. Here is a summary of current pricing:

  • Single test strip:

    • From S$11 to S$17.50 for one test strip (e.g., twoplus Fertility Ovulation Test Kit).

  • Pack of 5 test sticks/strips:

    • Around S$31.50 to S$32.30 (e.g., Guardian or Watsons Ovulation Test Kits).

  • Digital ovulation test (10 tests): From S$65 for a pack of 10 digital tests (e.g., Clearblue Digital Ovulation Test).

  • Bulk strips (30–40 strips):

    • From S$10.75 to S$11.72 for packs of 30–40 test strips, often available online via marketplaces like Lazada or Shopee.

  • Other brands (15 strips):

    • Around S$43.50 for 15 test strips (e.g., Artron Ovulation Test Kit).

In summary:

  • Basic strips:

    • S$10 to S$18 for single or bulk packs (more economical in larger quantities).

  • Mid-range (5 tests):

    • S$31 to S$33.

  • Digital kits (10 tests):

    • S$65 and above.

Prices may vary slightly depending on the retailer, promotions, and shipping options. Most kits are available at local pharmacies, online stores, and major e-commerce platforms in Singapore.

What are the advantages and disadvantages of using an ovulation test?

Advantages

Ovulation predictor kits help couples plan for pregnancies but come with pros and cons. Advantages of using an ovulation predictor kit include:

  • Ease of use:

    • Ovulation predictor tests are easy to use and work much like home pregnancy tests. Each kit includes several test sticks or strips, which let you test multiple times.

  • High accuracy:

    • Ovulation tests are 97% accurate in detecting an LH surge, making them highly effective at predicting ovulation.

  • Convenience and accessibility:

    • These kits are widely available over the counter at pharmacies and do not require a prescription. They are also more convenient and less time-consuming than daily methods like basal body temperature charting.

  • Helps target the fertile window:

    • Using ovulation tests can help couples time intercourse more precisely, which has been shown to increase the likelihood of conception compared to not using any ovulation tracking method.

  • Concrete results:

    • Ovulation tests provide a visible, objective assessment of hormone levels, which can be clearer than tracking physical symptoms alone.

Disadvantages

Disadvantages of using an ovulation predictor kit include:

  • Limited detection:

    • Ovulation tests detect the LH surge but do not confirm that ovulation has actually occurred. In some cases, an egg may not be released even after an LH surge (e.g., in luteinized unruptured follicle syndrome).

  • Not suitable for everyone:

    • Women over 40, those approaching menopause, or those with consistently high LH levels may get inaccurate results. Similarly, people with irregular cycles or those taking certain fertility drugs (like hCG) may find such tests unreliable.

  • Cost:

    • Ovulation test kits can be expensive, especially if you need to use them over multiple cycles.

  • Does not monitor all fertility signs:

    • Ovulation tests do not track other important fertility indicators, such as cervical mucus changes, which can also signal ovulation.

  • Timing and interpretation:

    • For best accuracy, tests must be done at the correct time in your cycle and often at a specific time of day. Misuse or misunderstanding of results can lead to missed fertile windows.

  • False positives and false negatives:

    • Some users may experience multiple LH surges in a month or inconsistent results, leading to confusion or missed opportunities.

In summary, ovulation tests are a convenient and accurate tool for many women trying to conceive, but they have limitations and may not be suitable for everyone. If you have irregular cycles or have been trying to conceive for an extended period without success, consult a healthcare provider for further evaluation.

FAQ

How many days before an ovulation test is positive?

An ovulation test typically becomes positive 24 to 36 hours before ovulation, marking the start of your most fertile period.

When should I start using an ovulation test kit?

Begin testing 3 to 5 days before your expected ovulation date. For a 28-day cycle, this is usually around day 10 or 11.

Can I get pregnant 2 days after a positive ovulation test?

Yes. Sperm can survive in the reproductive tract for up to five days, so having intercourse in the days following a positive test can result in pregnancy.

How do I know if I'm ovulating?

Besides using an ovulation test, you may notice physical signs such as changes in cervical mucus (clear and stretchy), mild pelvic pain, or a slight rise in basal body temperature.

Can you ovulate without a period?

It is possible, especially in women with irregular cycles or certain medical conditions. However, ovulation without menstruation is uncommon and should be discussed with a healthcare provider if suspected.

Are there any risks to an ovulation test kit?

Ovulation tests are safe and non-invasive. The main risk is misinterpreting results, especially if you have irregular cycles or certain hormonal conditions.

How long after a positive ovulation test do you ovulate?

You typically ovulate 12 to 36 hours after a positive ovulation test result.

Do ovulation kits really work?

Yes, when used correctly, ovulation kits are highly accurate in detecting the LH surge and predicting ovulation.

How long after flashing a smiley will I ovulate?

On digital tests, a flashing smiley usually indicates high fertility, while a solid smiley means peak fertility. Ovulation typically occurs within 24 to 36 hours after a solid smiley.

Can you get pregnant on high-fertility days?

Yes. Having intercourse during high fertility days (the days leading up to and including ovulation) offers the best chance of conception.

How long after ovulation will I test positive?

Pregnancy tests can detect pregnancy as early as 8 days after ovulation, but most are accurate from the first day of your missed period. If you have further questions about ovulation or fertility, consult your healthcare provider for personalised advice.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.

For more information, contact us:

Thomson Specialists Paragon (Health Screening)

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