Calculate when such an important event in your cycle as ovulation occurs, special tests will help. But how to use them correctly? Let’s figure it out. Try Kiara Harris of EasyToBeMom.

When does ovulation occur? Should I do a test?

A positive ovulation test result will help you find out when the next menstruation begins, because ovulation occurs 12-16 days before them.

However, it is not recommended to use the ovulation test as a method of contraception. The test determines the jump in luteinizing hormone (LH) 24–48 hours before ovulation. But sperm in the female body remain viable for 3 to 5 days. Therefore, conception can occur even if you have sex before the LH jump.

How to do an ovulation test?

One way to determine ovulation is a home test. It responds to a jump in luteinizing hormone in the urine.

Here are some test recommendations.

  • Use the test a few days before the expected ovulation (with a regular 28-day cycle, the test should be done on the 11-12th day).
  • Better spend them 2 times a day (but do not use the first morning urine).
  • Before performing the test, do not drink plenty of water and do not urinate for about 4 hours.
  • Follow the instructions carefully (collect urine in a clean container; place a test strip in it for no longer than 10 seconds; check the result no later than 10 minutes).
  • Continue to do tests until you get a positive result.
  • If the 2nd line is clearly visible, ovulation will occur within 24–48 hours, if weak, until ovulation is predicted.

To determine fertile days most accurately, during the cycle, you can additionally measure basal temperature, monitor cervical mucus and make a series of ultrasound.

How many times a day do ovulation tests

An increase in the level of luteinizing hormone in the urine shortly before ovulation varies in different women in duration and severity.

Sometimes the LH jump lasts only a couple of hours, and, therefore, can only be recorded during this period.

In order not to miss the jump in the hormone, it is better to do the test 2 times a day at regular intervals.

If the peak time is long (more than 24 hours), then one test per day is enough to track the jump in the level of LH in the urine.

If the test is positive (an increase in LH is determined), ovulation will occur within 24–48 hours.

Therefore, in order to become pregnant, it is recommended to have sex on the day when the test showed a positive result, and for the next 3 days.

When to do ovulation tests with irregular cycles

Typically, tests that respond to urinary luteinizing hormone (LH) levels are performed several days before expected ovulation.

If the cycle is regular, the initial data will be approximately as follows:

  • menstrual cycle duration: 28 days ;
  • the luteal phase (from ovulation to menstruation) is quite stable and lasts from 12 to 14 days ;
  • beginning of tests: 3 days before ovulation .

The total is: 28 – 14 – 3 = 11. Thus, tests should be carried out from the 11th day of the cycle (counting from the 1st day of your menstruation).

Irregular cycles complicate matters a bit.

It is best to determine the shortest cycle in the last 6 months and consider the current cycle as the shortest.

For example, your shortest cycle lasted 21 days, your luteal phase is stable and lasts 14 days.

21-14 = 7.

Therefore, ovulation is expected to occur on the 7th day. Thus, to start the tests should be 3 days before, on the 4th day of the cycle.

Ovulation tests will help you determine the duration of the luteal phase if it is more or less than 14 days.

Do ovulation tests have 100% accuracy?

Ovulation tests indicate the presence of luteinizing hormone (LH) in the urine. Within 24–48 hours after an increase in LH, follicle rupture and egg release (ovulation) occur. But sometimes this physiological process can be disturbed.

There are several reasons why ovulation tests can be inaccurate:

  • In the presence of polycystic ovary syndrome (PCOS), the test records a jump in LH, but ovulation may not occur.
  • In the case of luteinization syndrome of a neovulated follicle, the LH level is sufficient for detection by the test, however, the egg does not leave the ovary.
  • With violations in the work of the hypothalamus and pituitary gland, the production of LH is sometimes disrupted. For example, its level may be stably higher than the threshold determined by the test, or several peaks may be observed. In such a situation, a positive test will not show when ovulation actually occurs.

Thus, to track ovulation, it is better to use a combination of methods: tests + measurement of basal temperature + observation of cervical mucus.

What tests are there to track ovulation?

Now there are many different tests. They vary in price, accuracy, parameters for determining the approaching ovulation and ease of use.

The most common test strips and digital devices that detect an increase in the level of luteinizing hormone in the urine. They look like pregnancy tests.

The test can be done at home, it is quite inexpensive (compared with the ultrasonic method).

Test strips come in different sensitivities, which are measured in international units per liter, or ME / L. This parameter indicates the minimum amount of LH in the urine that the test can detect (10 to 40 IU / L).

This means that tests with high sensitivity (10 IU / L) are more likely to detect an increase in LH level, even if its peak value is low.

Some tests, in addition, determine a sharp jump in estrogen, which precedes an increase in LH. This helps to calculate the start of the fertility window earlier than when using the LH test only.

Differences between different ovulation tests

Most home tests record an increase in luteinizing hormone in the urine that occurs 24–48 hours before the egg leaves the follicle.

During this period and in the first 24 hours after ovulation, the chances of getting pregnant are highest.

In addition, there are test systems that detect in the urine an elevated level of not only LH, but also estrone-3-glucuronide (E-3-g).

E-3-g is a product of the decomposition of estrogen, its level in the blood and urine rises before the rise of LH. This helps to determine the time favorable for conception much earlier.

5 days before ovulation, a burst of E-3-g occurs, which indicates its approach. From this moment, you can begin to actively engage in sex: in anticipation of a mature egg, spermatozoa are viable in the female body for up to 5 days.

Positive result: what’s next?

A positive test result indicates a jump in LH. This means that ovulation should occur in the next 24–48 hours. And this is the best time to get pregnant.

However, this is not always the case. Therefore, in order to conceive, it is recommended to have sex starting from the day you receive a positive result and for the next 3 days.

If you are not sure about the result, refer to the instructions for use (included in the test kit).

In addition, the Flo app can provide valuable information to help you determine the best cycle time for conception.

Negative ovulation test: have you done everything right?

A negative test result means that you do not have a jump in LH and ovulation has not occurred. If you are not sure about the result, refer to the instructions that came with the test.

Predicting a LH jump is not easy, so don’t worry in advance if the next result is also negative.

To get the most reliable result, you can use other methods in addition to conducting tests. For example, measure basal body temperature and track changes in cervical mucus.

Be patient: do tests for at least 3 cycles. And also mark the results in Flo – the application will use them to build more accurate forecasts.

Negative Ovulation Tests: Causes

The ovulation test can be negative for several reasons.

  • LH concentration is too low to detect.
  • Peak LH is short-lived. Perhaps you missed it (which is why you need to do tests 2 times a day with a difference of 10 or more hours for several days before the expected ovulation).
  • The test was not performed correctly or you did not follow the instructions. For example, you used your first morning urine or it was diluted.
  • If you have long cycles, you may have done the test too soon. Start testing 17 days before your expected period or 3 days before possible ovulation. Continue until the result is positive.
  • Test performed too late on cycle. Perhaps the increase in LH occurred earlier than you expected.
  • In some cycles, ovulation does not occur due to stress, intense physical exertion, sudden changes in weight or an unusual climate.


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