Frequently asked questions for Ovulation Tests

  • What is ovulation, when does it occur and why it important?

    Whether you are thinking about trying for a baby or trying already, gaining a better understanding about how your body works can be a big help. One in two couples could be trying to conceive on the wrong days of the woman’s cycle3, so we’ve put together some information to help you understand your menstrual cycle and the ovulation process. Ovulation happens when hormone changes trigger your ovaries to release an ovum (egg) – usually 12 to 16 days before your next period starts. You are most fertile on the few days leading up to and including the day of ovulation.

    The ova (eggs) are contained in your ovaries. During the first part of each menstrual cycle one of the eggs will be prepared for release from the ovary. As you approach ovulation, your body produces more estrogen. This hormone causes the lining of your uterus to thicken and also creates a sperm friendly environment. The higher estrogen level triggers a sudden rise or ‘surge’ in luteinizing hormone (LH) which then triggers the release of the egg from your ovary, this is called ovulation.

    Normally, ovulation occurs 24 to 36 hours after the LH surge, and you are at your most fertile on the day of the LH surge and the day after.

    The egg survives for up to 24 hours after ovulation which is when it can be fertilized. If fertilization does not occur, the levels of the fertility hormones decline and the next cycle starts with the shedding of the thickened uterus lining (period).

    Although the egg only survives for up to 24 hours, sperm can survive for up to five days. That is why you can still conceive even if you have sex 4 -5 days before the egg is released.


    3 Johnson SR, Foster L and Ellis J. Human Reproduction (2011) 26: i236

  • I think I might be pregnant. What should I do?

    You could take a Clearblue® Pregnancy Test. They’re easy to use and can give you a result in as little as 1 minute. Clearblue® Pregnancy tests are over 99% accurate from the day of the expected period and most Clearblue® pregnancy tests can be used up to 5 days before a missed period. If your Clearblue® Pregnancy Test result is ‘Pregnant’ you should see your doctor to discuss your result and the steps you should take next. If you’d like to know more about Clearblue® Pregnancy Tests, click here.

  • I've done all the tests as instructed, but I’ve not yet detected my LH surge. What should I do?

    If you started testing on the correct day of your cycle according to the instructions and have not yet detected your LH surge, in most cases we would recommend that you buy another pack and keep testing. There is, however, further information below.

    If you are using Clearblue® Advanced Digital Ovulation Test and have seen 9 or more days of High Fertility this cycle, it is unlikely you will go on to detect your LH surge and see Peak Fertility. You may, therefore, want to stop testing for this cycle.

    Occasionally some women have an LH surge that is too low for the test to detect or they do not ovulate during a cycle. This is not unusual and may happen in approximately 8% of cycles1. If you have not detected your LH surge for 3 consecutive cycles we recommend you discuss this with your physician.

    1 In a study of 87 women, in the UK.

  • Do I need to use all the Clearblue® Ovulation Tests in the package?

    No. You can stop testing when you detect your LH surge and store the remaining tests in case you need them next cycle.

  • Do I need to compare my daily Clearblue® Ovulation Test results?

    No. Each test that you do will tell you your fertility status for that day.

  • I made a mistake during ovulation testing, what should I do?

    The best solution is to use another ovulation test again as soon as possible today (though you should wait 4 hours before passing urine again to ensure that the level of fertility hormones in your urine is not diluted). Try to avoid drinking excessive amounts between doing the ovulation tests. Make sure that you follow all the instructions carefully. It’s best not to wait until the next day to do another test, or you could miss detecting your fertile days. If you have collected a sample to test, then you can use this same sample straight away to do your second test. If you don’t detect your LH surge with this second test, then test again tomorrow at the usual time.

  • What are the highest and lowest fertile days?

    The days during each cycle when you are most fertile, and therefore most likely to get pregnant from unprotected sex, are the day of ovulation and the day before – these are the 2 days of peak fertility. There are also a few days before this when you experience high fertility and you also have an opportunity to get pregnant. Outside this ‘fertility window’ of about 6 days, the chances of getting pregnant are low.

  • What are the differences between ovulation and fertile days?

    'Ovulation' is the process of an egg being released from an ovary within the woman's reproductive system and this happens 12-16 days before the next period starts. A woman is at her most fertile on the day of ovulation and the day before.

    The 'fertile days' are all the days during a woman's menstrual cycle when she has the ability to become pregnant if she has unprotected sex. Due to the fact that sperm can survive for several days in a woman's body during her fertile time, a woman will have typically 6 fertile days each cycle, the day of ovulation and the 5 days before that.

  • Why do I need to know my cycle length?

    The timing of ovulation varies according to your cycle length, so to find out when you’re most fertile, you need to know your own body and cycle. You can work out the length of your cycle by counting from the first day of your period (Day 1) to the day before your next period starts. Ideally you’ll have this information before you start using an ovulation test.

    Cycle lengths differ from woman to woman and cycle to cycle but are usually between 23 and 35 days long.

  • How can I find out when I’m most fertile?

    There are a number of ways that you can find out when you are most fertile, one of the most simple and accurate is by using home ovulation tests such as Clearblue® Ovulation Tests and the Clearblue® Fertility Monitor.

    Clearblue® Ovulation Test or Clearblue® Digital Ovulation Test help you pinpoint the 2 most fertile days to conceive naturally, by detecting your LH surge.

    Clearblue® Advanced Digital Ovulation Test is the only ovulation test that typically identifies 4 or more fertile days1...that’s more than any other ovulation test. It tracks the changing levels of both LH and estrogen and its smart algorithm adapts to your personal cycle.

    Clearblue® Fertility Monitor is designed to identify all your fertile days2. It not only detects the LH surge and pinpoints your 2 peak fertility days, but can also identify the additional days of high fertility leading up to ovulation, by detecting the rise in estrogen. It also stores your cycle information and adapts its testing regime to your personal cycle.

    1 In a study of 87 women, 4 or more fertile days were identified in 80% of cycles using actual cycle length.
    2 Number of fertile days will vary. In a German study of 149 cycles, Monitor results correlated with serum hormone levels & ultrasound observed ovulation.

  • Do you have any tips* to help conceive and have a healthy pregnancy?

    The following tips may help you to give your baby a good start in life. *These are suggestions for information purposes only. Always consult a qualified healthcare professional for medical advice, in particular to monitor the progression and duration of your pregnancy. Please always read carefully the instructions provided with the product before use.

    • Take Folic Acid Taking folic acid as directed before start trying to become pregnant is extremely important as it means that there is enough of this essential vitamin in your body at the very earliest stages of pregnancy. Taking folic acid early can prevent neural tube defects (problems with the development of the spine, such as spina bifida).
    • Go for a physical check up Review your lifestyle e.g. alcohol and cigarette consumption, current medications and vaccinations, and ask your healthcare professional for general advice about getting pregnant and pregnancy.
    • Be a healthy weight Being overweight or underweight could cause difficulties in conceiving. Talk to your healthcare professional if you need help to know the best weight for you, and for advice on how to achieve and maintain that weight.
    • Get enough exercise This will help to tone and strengthen your muscles and make it easier to carry your baby. Once you are pregnant, pregnancy exercise classes are a good way to stay healthy as they are specially designed for pregnant women.
    • Boost your nutrition Your baby’s only source of nutrition will come from you. So make sure you get enough calcium, protein, vitamins and carbohydrates throughout your pregnancy. Avoid caffeinated drinks and unpasteurized dairy products – check the full list of food types to avoid with your healthcare professional.
    • Be mindful of medication Discuss any prescription or over-the-counter medications that you take with your doctor.
    • Avoid infections (for example toxoplasmosis) Always wash your fruit and vegetables, wear gloves for gardening or emptying litter trays and make sure your meat is thoroughly cooked.
    • Keep your dentist in the loop If you need dental work, let your dentist know you’re pregnant. Some treatments could be harmful to your baby.
    • Stay safe at work The guidelines on safety at work for pregnant women are very variable from country to country, so you should consult the professional organization responsible for giving advice on this subject where you live.
  • What are the chances of getting pregnant during the fertile days?

    The chances of getting pregnant will vary cycle to cycle and woman to woman and will be dependent on many variables such as the woman’s age, her partner’s age, their general state of health and lifestyle. In a study2, the chances of getting pregnant on each of the days during the fertility window were reported and are shown in the graph below:-

    Estimated likelihood of conception on days relative to ovulation

    2 Wilcox AJ., et al. NEJM (1995) 333: 1517

  • What is the difference between using most Ovulation Tests and the Clearblue® Fertility Monitor?

    Most ovulation tests detect the LH surge, a sudden rise of luteinizing hormone (LH), which occurs approximately 24-36 hours prior to ovulation. This is how they help you pinpoint the 2 most fertile days of your cycle - the day before ovulation and the day of ovulation itself. So, if you make love on these 2 days, you’ll be giving yourself the best chance of becoming pregnant.

    Clearblue®Advanced Digital Ovulation Test is the only ovulation test that is different – it accurately tracks 2 key fertility hormones to typically identify 4 or more fertile days4, that’s more than any other test. This means you have more time in advance of ovulation to plan quality time together with your partner and you have more opportunities to get pregnant each cycle.

    The Clearblue® Fertility Monitor can identify more fertile days than any ovulation test – typically up to 6 days each cycle. It not only detects the LH surge and pinpoints your 2 peak fertility days, but also identifies typically 1-5 additional fertile days when you may conceive (high fertility days) by detecting the rise in estrogen which occurs immediately before this LH surge. As your partner’s sperm can survive in your body for several days, making love on those days can also result in pregnancy. It also gives you personal information, telling you when you need to test and when the end of your cycle is due

    4 In a study of 87 women, 4 or more fertile days were identified in 80% of cycles using actual cycle length (2012).

  • I've recently stopped taking the contraceptive pill / using a contraceptive injection. Does this affect my result?

    No, it will not affect your results. If you’ve recently stopped taking the pill your cycles might be irregular, so it may be harder to know when to start testing. For this reason, it might be a good idea to wait until you’ve had two natural menstrual cycles in a row, and note the length of these cycles, before using a Clearblue® Ovulation Test.
    With contraceptive injections it may take a while for your cycle length to stabilize and for your fertility to return, so you may need to wait longer before using a Clearblue® Ovulation Test for the same reason as above.

  • My cycle is outside the range shown in the table. How will I know when to start testing?

    If your cycle is 21 days or less, you should start testing on day 5 of your cycle. If your cycle is longer than 40 days and you are using either Clearblue® Ovulation Test or Clearblue® Digital Ovulation Test, you should start testing 17 days before you expect your next period. If your cycle is longer than 40 days and you are using Clearblue® Advanced Digital Ovulation Test, you should start testing 20 days before you expect your next period.

  • I've used Clearblue® Ovulation Tests for several months and haven't got pregnant. Can I be sure of getting pregnant?

    It can take normal, healthy women many months to conceive. There are many reasons why you may not get pregnant, even if you've made love at your most fertile time. So keep trying. If after several months of trying you've had no success, it’s advisable to go to see your physician to find out more about your next steps.

    In many countries, your physician will usually expect you to have been trying to get pregnant for a year if you are under 35 yrs old or for 6 months if you are 35-40 years old, before they will consider further investigation. If you are over 40 years old then you should ask for advice immediately.

    You may also want to learn more about the Clearblue® Fertility Monitor, it’s designed to detect all your fertile days1.

    1 Number of fertile days will vary. In a German study of 149 cycles, Monitor results correlated with serum hormone levels & ultrasound observed ovulation.


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Digital Ovulation Test: pinpoints your 2 most fertile days

In every cycle there are only a few days when a woman can conceive, so having sex on these days is very important if you are trying to get pregnant.