Saliva ovulation tests: How are they used and are they reliable?

By (embryologist), (embryologist) and (biochemist).
Last Update: 07/14/2022

The saliva ovulation test, also known as the saliva ferning test, is one that women can easily perform at home to estimate their most fertile days.

It has the great advantage of being reusable, proving an economic benefit over urine ovulation tests. However, the accuracy of saliva ovulation tests in determining the day of ovulation has been questioned. So, at present, they are infrequently used.

Why detect ovulation?

When a couple is trying for pregnancy, it is of key importance to know when ovulation occurs. Ovulation is the release of the egg from the ovary and occurs about 14 days before the next menstrual period.

This moment, and the days surrounding it, are when the encounter between egg and sperm, therefore, gestation, are likely to occur. These days are thus known as the woman’s fertile days.

As such, there are several methods, like the saliva ovulation test, that a woman case use to estimate when she will ovulate. These help her to know when pregnancy is most likely to occur, and have sexual intercourse during those days.

Nonetheless, trying for a baby should not become something scheduled. Ideally, sexual intercourse should take place every two days or so during a woman's fertile days.

What is a saliva ovulation test?

A saliva ovulation test is a small, reusable device. The woman can use it at home to estimate naturally when ovulation will occur. It is, in fact, similar to a small microscope.

There are several models of saliva ovulation tests, but all of them are usually quite discreet. The most common saliva ovulation test microscope are in the shape of a lipstick or compact, depending on the make and model.

In this type of ovulation test, the woman only needs to use a drop of saliva. These tests have a small lens to observe the deposited saliva sample once it has dried in the air. In this manner, the salivary changes that occur as ovulation approaches can be detected.

How do saliva ovulation tests work?

Levels of estrogen increase in the first half of the menstrual cycle (follicular phase) as ovulation approaches. This is accompanied by a rise in the amount of salivary electrolytes.

If you air dry a sample of sailva during this time, a crystallized structure appears, known as "fern leaves". This is because of its similarity of the pattern to the plant.

By using a saliva ovulation test, the woman can estimate when ovulation will occur a few days before it happens. To perform the test, simply place a saliva sample on the device, wait for it to dry, and observe the crystal pattern through the built-in lens.

Interpretation of test results

When this type of ovulation test is used, the resulting crystal pattern allows the woman to know whether or not she is in the periovulatory period.

As such, the woman needs to learn how to correctly interpret the different results or patterns of the saliva ovulation test. These are explained below:

  • Isolated spots: this pattern is present from the first day of the cycle (first day of menstruation) until a few days before ovulation. Therefore, it is a time when the woman is not fertile.
  • Some lines and small ferns: a pattern including some small ferns is observed in the days preceeding ovulation, indicating that the release of the egg is near. As sperm can survive up to 3-5 days in the female reproductive tract awaiting the egg, it is possible for a woman to become pregnant when she sees this pattern in the salivary ovulation test.
  • Defined ferns in the whole sample: this pattern indicates that ovulation is going to occur very soon or has just happened, so it is the woman’s most fertile moment.
  • Some lines and fading ferns fading: in the postovulatory phase, the ferns will fade and the woman sees lines and dots.

Thus, the test user easily knows if she is in her most fertile period or not. In the beginning, it is recommended that the test be done daily. This allows the woman to become familiar with the different patterns observed throughout the menstrual cycle.

How to perform a saliva ovulation test

Before performing the saliva ovulation test, it is important for the user to carefully read all of the instructions of her particular test. The general procedure for the correct use of the saliva ovulation test is as follows:

  • You can test at any time of the day, but never after eating, drinking, brushing your teeth or smoking. In these cases, it is best to wait 2-3 hours before testing.
  • Take a sublingual saliva sample (from under the tongue). This step can be done with a clean, dry finger.
  • Place the saliva on the glass, taking care not to let any bubbles form, and remove any that may have formed.
  • Wait for the saliva to dry. It is important to wait for this to occur naturally, which can take about 5-20 minutes.
  • Look at the sample through the lens and interpret the results.

Saliva ovulation tests are reusable. After use the woman should wash the glass carefully, without soap, with a soft cloth.

Advantages of saliva ovulation tests

Saliva ovulation tests are easy to use, discreet, convenient and readily available in pharmacies.

Furthermore, you can reuse a salivary ovulation test over several years. Hence, these particular tests may be more economical in the long run than ovulation tests that detect the LH hormone in urine.

Disadvantages of saliva ovulation tests

One of the disadvantages of saliva ovulation tests is that they require a learning period and practice until the woman easily recognizes the different crystallization patterns in saliva. In addition, interpretation of results is subjective.

There are moderate results in the accuracy and reliability in predicting the day of ovulation with these tests. Together with the possible difficulties of interepreting the results, these can decrease their usefulness.

Such reasons are perhaps why saliva ovulation tests are generally less known and less used than urine ovulation tests. However, they could be a good option in combination with other methods of estimating ovulation, such as measuring basal temperature, cervical position or the appearance of the cervical mucus. You can read more about these other methods for predicting ovulation in the following article: What are the signs of fertility in women

FAQs from users

How much does a salivary ovulation test cost?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

Saliva ovulation tests have a price that can vary depending on the brand, model and country.

In Spain they usually range from €35 to €65 euros. In the UK they can be found for around £20 - £50. The US market has prices between $20 - $40.

However, saliva ovulation tests are reusable, so in the long run they can be cheaper than strips that detect LH in urine (urine ovulation test).

Is there a way to do the saliva ovulation test faster?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

No. In order to carry out the saliva fern test correctly, the saliva must be allowed to dry naturally in the air. To do this, you need to about 5 - 20 minutes.

Therefore, you must not use a hair dryer or any other way to accelerate the drying process.

How do you take the saliva sample for the ferning test?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

You can collect the saliva sample for an ovulation test (or fern test), directly with her finger. However, it is important to have previously washed and dried your hands, so that the finger is clean and dry.

In general, it is best to collect saliva from under the tongue. It is also important not to have brushed your teeth, eaten, drunk or smoked in the previous 2-3 hours.

If you want to learn more about urine ovulation tests, you can read the following article: Ovulation tests: how do they work and what is their purpose?

If you would like to read more in depth about the menstrual cycle, we recommend visiting this link: The different phases of the menstrual cycle.

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FAQs from users: 'How much does a salivary ovulation test cost?', 'Is there a way to do the saliva ovulation test faster?' and 'How do you take the saliva sample for the ferning test?'.

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Authors and contributors

 Laura Rollán Guilén
Laura Rollán Guilén
Bachelor's Degree in Biology from the University of Valencia (UV). Specialist in Human Assisted Reproduction. Writer of scientific contents. More information about Laura Rollán Guilén
 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV
Adapted into english by:
 Michelle Lorraine Embleton
Michelle Lorraine Embleton
B.Sc. Ph.D.
PhD in Biochemistry, University of Bristol, UK, specialising in DNA : protein intereactions. BSc honours degree in Molecular Biology, Univerisity of Bristol. Translation and editing of scientific and medical literature.
More information about Michelle Lorraine Embleton

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